Waterchange water advanced question

[68551]

I read an interesting theory that I have never heard before that the premixed saltwater you have ready for waterchanges should have a bucket or 2 of current tank water mixed with it for a couple days prior to a waterchange....The idea is that the bacteria has a chance to multiply so you have better (more matured) water going in your tank with each waterchange....
Any thoughts????

[newtank]

I have read that most of the microbial population found in the average tank are not free swimmers, those that are will canibalize each other for food as the ASW will have little in the way of nutrients to support them? I'm certainly not the definitive authority so I'm interested as to how the collective views this concept.

[DLANDINO]

Interesting, it may be better answered in the Reef Chemistry forum though. Calling Boomer or Randy!!!!

[buffalo123]

If the water change is to reduce nutrients and buildup of whatever in the water, is it not counterproductive to add old tank water to the new water prematurely.

[68551]

I wish I could find the article again but it was said to help "season" the water & to make less of a transition to the main tank.

[Frogmanx82]

I can't see how this would be worth doing.

[68551]

I do so much reading I couldn't remember where I found the info but I have found it....On page 94 (middle column half way down under Salt Mix Rehydration) of THE CONCIENTIOUS MARIE AQUARIST Robert Fenner states "I recommend mixing your synthetic seawater a week or more in advance of use....I also like to add a few cups of "live" system water, inoculaating the mix with microbes and enzimes from an established aquarium. This will go a long way toward readying the new water biologically and chemically for use."

[reefgeezer]

Could it be that besides adding some microbial content, the old salt water helps reduce the stress of the water change by reducing the ORP a little.

[68551]

It seems to me that the more similar the changeout water & the tank water are the easier it would be on corals & fish when it is added...I"m not sure if the system water should be added right before the water change or when you mix up the water at the start

[Hartdude]

Just a routine water change has never caused noticable stress to my system. Why fix something that isn't broken? I know, just trying to improve upon a known process.:rollface:

[lordofthereef]

I think this is bogus personally. As said above, very little (if not none) of the microbial population we care so much about is suspended in the water column. You are going to have far greater benefits with oxygenating the water and getting it at the same emperature as that in your system IMO.

[68551]

Do you se any benefits at all to adding tank water to the waterchange water if all of the other parameters in the water are the same???

[chefzif]

You are only makeing a 10% change so this process will not have a signifgant difference in you r water change keep water temp and salinity the same as the tank and make your water change and all will be great!

[68551]

You are missing the point....All things being equal....Same temp, same salinity, same ph etc,etc....Do you see ANY merit in doing the above?????
Why would Robert Fenner suggest this approach????

[John Zillmer]

You are missing the point....All things being equal....Same temp, same salinity, same ph etc,etc....Do you see ANY merit in doing the above?????
Why would Robert Fenner suggest this approach????

Well, if all things were equal, then there would be no merit in doing the water change at all, right? I mean, what would the point be, since you'd be replacing water with exactly identical water. The very idea behind a water change entails that the water you change is chemically different than the water you replace it with.

[68551]

No I don't mean that the 2 waters are exactly the same....Of course there are impurities in the tank water that need to be removed (organics, fish urine & poo & depleated minerals) My "all things being equal" comment was regarding the physical parameters of both waters with regards to temp, sg, & alk.....Whch brings me back to my 3 main questions.....

1. Do you see ANY benefit to adding some tank water to your waterchange water?
2. If it does nothing then why would Fenner suggest it???
3. If you see a benefit would it be better to add it when first mixing the water & salt (in the Brute container) or right before a waterchange?

[John Zillmer]

Robert Fenner states "...I also like to add a few cups of "live" system water, inoculaating the mix with microbes and enzimes from an established aquarium. This will go a long way toward readying the new water biologically and chemically for use."

OK, the issue here seems to be in the italicized passage. As other posters have pointed out, this sounds like BS. The water, once mixed with salt mix and adjusted to the few major parameters that reefers think are important, is biologically and chemically ready for use. Plus, these "microbes and enzymes" are already in the system, so why take them out only to add them back? (Yeah, they'll reproduce in the Brute can...okay...uh huh...)

Why would Fenner say this, then? You could email him at wetwebmedia, but (no offense intended) I don't think that he will give an answer that is any less vague. I'd enjoy being proved wrong on this, though:)

[68551]

"Why would Fenner say this, then? You could email him at wetwebmedia, but (no offense intended) I don't think that he will give an answer that is any less vague. I'd enjoy being proved wrong on this, though"

I have posted to WetWeb as you suggested & will add any replies.....Sue

[Frogmanx82]

I think the extra step makes water changes more of a hassle. You are adding a whole conditioning step that is unnecessary and time consuming if you really need two wait a day or two. The net result would be fewer water changes which would negate any minimal benefit this would provide.

While in theory this may have some small merit, in practice its a waste of time. I don't care what else Fenner has to say about it its a poor recommendation.

[68551]

Follow this link for the thread & posts in Wet Web...
http://bb.wetwebmedia.com/viewtopic.php?f=23&t=2647

[John Zillmer]

2 points:
-- emailing Mr. Fenner will be more productive than another forum debate. You can email him from the front page of WWM.com, if things are like they were last time I visited the site.

-- "it will take off the antiseptic edge to the water"?!?! Maybe after the unjustified ad hominem attack on Frogmanx82 I was ready to be critical, but...

[68551]

Tried to find a way to get this to the WWM crew so hopefully Bob will give us an explanation soon....

[Luckylouse]

Man does that ever sound like a pain in #$$. I guess if you did a larger water change I could see the need to condition the water but small water changes would be better IMO.
I do a 8-10% water change every Sunday. Keeps trace elements line-up and everything is happy. It takes me 20 mins max every week to do a 10% water change and scrape the glass a do a little coral inspecting.

[scolley]

... Inhave never heard before that the premixed saltwater you have ready for waterchanges should have a bucket or 2 of current tank water mixed with it for a couple days prior to a waterchange
... How is this conversation even occuring without discussing the VOLUMES of seed water needed with respect to the target volume of water to be changed?

In my tank "two buckets" of the smallest possible buckets would likely exceed the total volume of my daily 0.5g water change. At the same time 2 buckets (of any reasonable size) be likely meaningless in a very large (100's of gallons) water change.

Apologies for picking nits... But the fact is that any discussion of the value of such a technique is difficult to divorce from the ratio the seed water to the target volume of water to be changed.

That is to be excepted by the opinion that no ratio of seed water to changed water, no matter how large matters (ex. 99 or 100%).

[Luckylouse]

regardless in ratios I still think many small water changes ( ie: once per week. 10%) is ideal for me. Seeding the water IMO is not necessary unless you are doing a large W. Change.

[scolley]

regardless in ratios I still think many small water changes ( ie: once per week. 10%) is ideal for me. Seeding the water IMO is not necessary unless you are doing a large W. Change.

Ah ha! I see that I did not make my point clearly enough, because I believe you are disagreeing with me... Yet I am in compete agreement with you. ;)

The bottom line is that this is all about ratios. If I'm changing 1 gallon a day in a tank that's 1,000 gallons... It's really hard to believe that seeding matters. But if we are talking about changing 500 of those same 1,000 gallons... Suddenly the question seems to be worth discussion.

The point i'm trying to make is that whether this discussion is worth having - at all - is entirely dependent on ratios. In this case, the ratio of change water to the total target system.

[Luckylouse]

lol. Drinking Scotch.... I feel the need to argue even when we are in agreement! lol.

I do agree!

[scolley]

lol. Drinking Scotch.... I feel the need to argue even when we are in agreement! lol!
Ah... A kindred spirit! Hail fellow well met... ;)

[Luckylouse]

Scolley, When are you taking the training wheels off?

I've been in the hobby 9 months and my 90 gal is now to small! Upgrading in February!

Thought I'd fire you up little.

[Frogmanx82]

The link was pretty funny. Attacking me for calling a fish by its common name and when did having 4 clownfish in a tank suddenly mean my 35 years of keeping fish is suddenly invalidated. By the way its 7 months and the clowns are great.

Since his name was clownfish, maybe he was hypersensitive to their plight. In any case I'm sorry he felt he had to quit posting here.

Obviously that was the only thing that could be attacked because my argument is sound. Making water changes more time consuming is going to hurt rather than help the situation. Bob needs a lot more qualifiers on his recommendation for it to make any sense.

[scolley]

Scolley, When are you taking the training wheels off?
Soon! Pls check this thread in a few days... http://www.reefcentral.com/forums/showthread.php?t=1662912

Should show a decent 6 month tank. But gotta learn how to use that new Christmas camera first. :)

(Apologies to the OP, sorry for the off-topic... )

[Luckylouse]

Soon! Pls check this thread in a few days... http://www.reefcentral.com/forums/showthread.php?t=1662912

Should show a decent 6 month tank. But gotta learn how to use that new Christmas camera first. :)

(Apologies to the OP, sorry for the off-topic... )

Cool!

Here's my 9 month old tank.

<a href="http://s690.photobucket.com/albums/vv266/Luckylouse/?action=view&current=FTSDec290912-29-200910-15-33PM3072x.jpg" target="_blank"><img src="http://i690.photobucket.com/albums/vv266/Luckylouse/FTSDec290912-29-200910-15-33PM3072x.jpg" border="0" alt="FTS Dec29.09"></a>

This is an 8 month old shot.

<a href="http://s690.photobucket.com/albums/vv266/Luckylouse/?action=view&current=IMG_6782.jpg" target="_blank"><img src="http://i690.photobucket.com/albums/vv266/Luckylouse/IMG_6782.jpg" border="0" alt="FTS"></a>

[68551]

Sorry for opening a can of worms!!!! I want to go on record noting that Bob said to add a cup or 2 of tank water not buckets as I said in the beginning of my thread before I could find the actual article....I would really like Bob to tell us the ratio of seasoned to new water if he ever responds....
I don't see how scooping up a cup or 2 & dumping it in the waterchange bucket is a big deal enough to make people put off doing waterchanges especially if it is when you have the measuring cup in your hand anyway to add salt to the plain water to start mixing....
Yes, some people had sucessful tanks before skimmers & MH lights but if something small comes along that is easy to do & would "Help" in some small way to destress the occupants of our tanks then I am all for it....I am a bit obsessive about my tank & when I had a HA breakout early on I spent over 8 hours many days picking it off the rocks with tweezers while I performed water changes & stopped overfeeding to get to the root of the problem. I thought the exercise of this forum was to find better ways to do things....It may not make a difference to US because we don't notice any change in our livestock but if it makes a difference to THEM (the livestock) then I'm all for it....
I change out 15-20% once a week in my 100+ gal tank.....I don't claim to know as much as anyone who has been in the hobby for decades but my 4 years have taught me a lot & I have an "inquiring mind" & I intend to keep learning as long as I am breathing....Please be nice to each other & lets all study the "Possibility" that there could be some merit to this technique....

Ps....A personal email has been sent from my email directly to Bob this morning @ 6:32......

[Daniel Reef]

Let us know what Bob says. I think the poster was trying to say that the deterrent factor would be the additional wait time to let the water get "seasoned" by the new salt. Some people may not have the patience or opportunity to wait for days to complete a water change. I am confident that if this is a helpful procedure that can be documented, then more individuals will likely adopt it because it certainly is a very minimal cost procedure compared to buying a skimmer or purchasing halides. Only time will tell.

[Frogmanx82]

I'm not sure how the benefits can be documented or what conditions they would even attempt to demonstrate. Is there a way to measure the harshness of the water? What percent water change would trigger concern about the water's harshness? What makes the water less harsh and are any other additives beneficial to the conditioning process?

The idea is worth following up on, but at the moment I think its premature to suggest people start doing this. There has been no benefit demonstrated for the effort involved.

[wickedfood]

You are missing the point....All things being equal....Same temp, same salinity, same ph etc,etc....Do you see ANY merit in doing the above?????
Why would Robert Fenner suggest this approach????

Because there's merit to it, and he states basically why. I think he implies that it's not necessary, just a step further in keeping your water chemistry that much better. To have gone into it further in that basic book would have been chemistry overkill. He also recommends adding your salt mix 24hrs after your source water has been aerated and heated. I do neither of these things, admittedly due to laziness.

[reefgeezer]

I'm not sure how the benefits can be documented or what conditions they would even attempt to demonstrate. Is there a way to measure the harshness of the water? What percent water change would trigger concern about the water's harshness? What makes the water less harsh and are any other additives beneficial to the conditioning process?

The idea is worth following up on, but at the moment I think its premature to suggest people start doing this. There has been no benefit demonstrated for the effort involved.

ORP - Besides being an indicator of water quality it also indicates how much oxidizing potential (harshness?) the water has. If you have the capability, check newly mixed salt water some time.

[Frogmanx82]

ORP - Besides being an indicator of water quality it also indicates how much oxidizing potential (harshness?) the water has. If you have the capability, check newly mixed salt water some time.

Hasn't this already been done somewhere? A few charts or graphs to look at would be nice

[68551]

http://www.bostonreefers.org/forums/showthread.php?t=47126

[Frogmanx82]

Interesting but the jury seems to be out on a) how to reliably measure ORP b) the effects of high or low ORP and c) should we try to regulate ORP and if so how.

Does ORP entirely encompass the nebulous term "harshness" for saltwater quality?

I could splash some peroxide in my make up water to increase the ORP. I'm not sure I'm ready for the can of worms to be opened here though I'm sure some will be all over it. Its another gadget to get.

[68551]

For those of you waiting to hear Bobs answer....Here it is at the end of the posts.... http://bb.wetwebmedia.com/viewtopic.php?f=23&t=2647&p=27274#p27274

[mgustin]

Because there's merit to it, and he states basically why. I think he implies that it's not necessary, just a step further in keeping your water chemistry that much better. To have gone into it further in that basic book would have been chemistry overkill. He also recommends adding your salt mix 24hrs after your source water has been aerated and heated. I do neither of these things, admittedly due to laziness.

I personally have always premixed my water at least one week in advance. 1.) you always have water ready to go in case of emergency
2.) I know the water has a matching temp, s.g., pH, dKh etc..because I have time to adjust it.
3.) You only need to aerate source water that is RO/DI. Why? To drive off CO2 generated in the RO process. By driving off the CO2 prior to mixing the salt, the pH will increase in the RO water and you won't eat up buffers in the salt mix.

By pre-mixing your water at least 24 hrs ahead of time, you will provide more stabillity to the tank. I've measured s.g. in my change water 1 hr after I add the salt and again after 24 hrs and it does move up overnight slightly. I'm talking from 1.024 to 1.025. I'm using Tropic Marin Pro, so this isn't a result of poor quality salt mix.

I have a 90 gal reef, and I store 29 gal of pre-mixed water in a tank in the closet next to my reef. I perform a 10 gal water change every week by siphoning the water out, and then I use a pump in the 29 gal tank to backfill the display via a closed loop manifold. Takes less than 15 minutes to change the water. I then fill the 29 back up with RO/DI water that is in another contanier in the same closet that is aerated with a powerhead 24/7 and add the salt. I also have an ATO unit in the closet under the 29 gal tank. It takes me very little effort to do water changes with my pre-mixed water, and I fill my ATO container about once every 2 weeks with aerated RO/DI water and buffer.

There are many benefits to pre-mixing water ahead of time, adding a cup or two of tank water to it when the salt is added will not extend the time required to pre-mix at all. You all can debate the effects of adding a cup or two of tank water all you want, but arguing that it adds time to the process isn't valid. Unless that is of course you aren't pre-mixing your water to begin with...which begs the question why wouldn't you?

[John Zillmer]

For those of you waiting to hear Bobs answer....Here it is at the end of the posts.... http://bb.wetwebmedia.com/viewtopic.php?f=23&t=2647&p=27274#p27274

It was very considerate of Bob to take time to address the question. Unfortunately, I don't think he said much more than already has been said. The bulk of the info he gave (regarding the premixing procedure itself) is in this passage:

"The overall benefit of such mixing of new and old water is to discount the chemical and physical "new-ness" of the change-out water. How to put this... tap/mains water is proving more variable and synthetic salt mixes much more so in recent years. Blending in the life in the new water days ahead will generally help to reduce/dampen these potential "difference" effects."

I don't know of any reason to think that mixing in some tank water to this "variable" tap water/salt mix blend (that is, if anyone is foolish enough -- yes, I mean foolish -- to use tap water in a marine tank) will reduce this variability beyond the mere dilution of new water with a small quantity of old. I mean, putting this "life" in the new water will not remove chloramine or residual pesicides/herbicides, add or remove any noticeable amount of Ca or Alk, etc. There simply seems to be no grounds to believe that any of this would happen, and he does not offer any such grounds.

[68551]

I think the closer the changeout water is in composition to the tank water the easier the transition at waterchange time will be for all of the inhabitants of the tank....
If your changeout water is similar enough to the tank water that you don't see a value in the method then why is it we never encourage a 75-90% waterchange....Obivously it would be too stressful on the tank....If you choose not to do it I'm sure as Bob put it your inhabitants won't suffer any obivious stress....But I believe if I were a fish living in a tank as opposed to the vast ocean would be more stressful....I see a value to it so I already have my old & new water mixing so I will be ready for tomorrows waterchange....

[Frogmanx82]

I've always mixed my salt prior to addition but prior to going to a reef tank, I just used tap water with a carbon filter. When I switched to a reef tank this summer, I started buying rodi water. Now that I have a rodi system I need to have a storage system set up so premixing the saltwater is making more sense.

So if I do that, then putting a cup of tank water in the mix is no big deal. Is aeration needed as well or will a koralia generating some surface agitation be sufficient?

Would you add phyto to the mix as well?

I'm still not clear on what "harshness" or "newness" is with regard to the water quality in any measurable terms. I don't think ORP is the total picture.

[68551]

Yes, I keep a mag 5 in the brute container running constantly 24/7 as soon as it is full enough to stay submerged under water....The Brute also has a heater & thermometer in it.....I have never used the water for a waterchange sooner than 3 days after I have added the salt....
I use DT's Photoplankton which needs refrigeration so I would not add that to the Brute container ...
"Harshness".....Think of it in terms of changing out 80% of your current tank which you would never do....WHY???? Because it is "Harsh....No matter how long you season it in a Brute container....I think the addition of a couple cups of tank water would help soften it....
If I had a major disaster in my DT I would feel a lot better about changing out more water if it was seasoned for a few days with the current tank water....
That is what made me make my final decision to do it!!!!

[Booby damino]

I like to add two spoonfuls of dannon yogurt to my RO water 2 days before I put it in the tank.. the bifidus regularis in it keeps the tank healthy and all the fish regular. I'm surprised this hasn't been discussed as well known reef specialists have been doing this for years.

[Frogmanx82]

I like to add two spoonfuls of dannon yogurt to my RO water 2 days before I put it in the tank.. the bifidus regularis in it keeps the tank healthy and all the fish regular. I'm surprised this hasn't been discussed as well known reef specialists have been doing this for years.

Well that would seem to make the water less harsh. I wonder what Mr. Fenner has to say about that.

[Booby damino]

Frogman!... check your tank IMMEDIATELY.. that was post 666 for you.. baaaad juju!...( a spoonful of yogurt might save it though ) :)

[waldomas]

I like to add two spoonfuls of dannon yogurt to my RO water 2 days before I put it in the tank.. the bifidus regularis in it keeps the tank healthy and all the fish regular. I'm surprised this hasn't been discussed as well known reef specialists have been doing this for years.

Well...now we're being rediculous! :)

How about adding some macro algae and a light overhead?
Will that raise ORP? I don't know, just asking.

[John Zillmer]

Well...now we're being rediculous! :)

How about adding some macro algae and a light overhead?
Will that raise ORP? I don't know, just asking.

Putting macro straight into freshly mixed sw seems like a good attempt at killing it; at least it is not going to do the macro (or the ORP) any good, being in water with no nutrients. I suppose this is also true about tossing a cup full of Magic Living Tank Water (sounds like a Marc Weiss product!) into freshly mixed sw...poor little pods and bacteria will never know what hit them...

Back in the Dark Ages of (mostly freshwater) aquarium keeping, there was a mythology surrounding the practice of coveting 'old water', since tanks full of old water tended to keep fish alive pretty well. This myth stemmed from the basic misunderstanding of biological filtration via nitrifying bacteria; 'new tank syndrome' wasn't understood the way it is now. The present discussion reminds me of that. I have yet to read one bit of plausible scientifically grounded support in favor of this premixing. Actually, the only idea that makes sense in all this is the one regarding Dannon yogurt:spin1:

[Frogmanx82]

I have yet to read one bit of plausible scientifically grounded support in favor of this premixing. Actually, the only idea that makes sense in all this is the one regarding Dannon yogurt:spin1:

I tried making that point and got slammed for it. Don't you realize this is Bob Fenner we're talking about. If he said it, it must have some merit.

[John Zillmer]

I tried making that point and got slammed for it. Don't you realize this is Bob Fenner we're talking about. If he said it, it must have some merit.

Of course you got slammed, frogman -- after all, you call an Ophioderma sp. sea star a serpent when in fact it is not a snake at all...what would you possibly know?!:hmm3:

While there has been some little bit of interesting information referred to regarding ORP, and many nice but ultimately non-explanatory posts here regarding personal water change habits, this thread has basically been a dead end. What has been forgotten, I think, is that the burden of proof is on the camp who think there is some merit at all to premixing tank water with newly mixed SW. The reason the explanatory burden is on that new idea (though I've accused the idea of sounding old and primitive, it is a new idea to anyone who first began keeping aquariums in the last 50 years or so) is because the current common practice of making water changes solely with freshly-prepared SW has scientifically documentable benefits, is anecdotally quite beneficial, and has (to my knowledge) no evidence that there is anything like this so-called "harshness" about it.

If anyone tries this premixing strategy in any sort of a consistent manner, please do document any chemical, biological or even anecdotal results you notice, and please try to come up with some plausible mechanism for the occurrence of the results you document. Until then, this premixing idea has as much plausibility as crystal power, vortexes and ouija boards.:thumbdown

[mgustin]

Closed minds are like closed books: just blocks of wood.

[mgustin]

I've always mixed my salt prior to addition but prior to going to a reef tank, I just used tap water with a carbon filter. When I switched to a reef tank this summer, I started buying rodi water. Now that I have a rodi system I need to have a storage system set up so premixing the saltwater is making more sense.

So if I do that, then putting a cup of tank water in the mix is no big deal. Is aeration needed as well or will a koralia generating some surface agitation be sufficient?

Would you add phyto to the mix as well?

I'm still not clear on what "harshness" or "newness" is with regard to the water quality in any measurable terms. I don't think ORP is the total picture.

"Harshness": When mixing new salt water, there are many internal chemical reactions going on. By premixing the water well in advance (at least 24 hrs) you provide time for all of those reactions to complete and for the mixture to become stable. For example: If you measure the dKH, pH, and Ca of newly mixed water, and then measure it again in a couple of days, you may see the dKh increase, and the Ca come down a bit. Since there is no life present in the container to consume Ca, the only explaination is that the chemical reactions have completed and the water has become more stable. Letting your water circulate, aerate, and age a few days prior to use allows the water to come to an equilibrium. An equilirium between dissolved oxygen and carbon dioxide levels as well as all of the other internal chemical reactions taking place within the salt mix. Newly mixed saltwater is far more corrosive and caustic than aged water and that can be hard on equipment as well as your live stock.

Now....what you have to decide is if you want to add water to your tank that you mixed up 5 minutes ago or water you allowed to age a bit. I'm not going to debate the addition of tank water. I'm not qualified to do so...but it is an interesting topic. I respect Bob for his contributions to the hobby as well as his experience. If Bob says that it has benefits, I would search long and hard before I would question his judgment. IMO, it is possible that by adding a couple of cups of tank water to the premix, it may help reduce undetectable levels of the compounds that nuisance algae use as fuel.

In the past, I have had issues with cyano as most of us have. I'm not talking about full blown outbreaks, just some patches on the substrate and back of the tank. I noticed that everytime I did a water change, it would increase in growth and then subside again. I eventually changed salt mixes and it went away. Now...what was it in the salt mix that I couldn't measure that made it grow right after a water change? Who knows....but changing salt brands erradicated the little bit of cyano that I had. Someone suggested adding a cup of tank water to me at that time, but I never tried it. I wish I had. Would be interesting to know if it would have helped.

[noahm]

I do not see how it would hurt, but I don't see the benefit being anything truly significant. I place it up there with having the water the exact temp. I've been in spots where cold fresh water is coming up out of the sand and getting washed all over corals in the wild. Some things are critical and others just aren't. On a big big water change, it might very well help if you are 'seasoning' it for a week or so. Throw in a piece of LR for that matter.

[John Zillmer]

"Harshness": When mixing new salt water, there are many internal chemical reactions going on. By premixing the water well in advance (at least 24 hrs) you provide time for all of those reactions to complete and for the mixture to become stable. For example: If you measure the dKH, pH, and Ca of newly mixed water, and then measure it again in a couple of days, you may see the dKh increase, and the Ca come down a bit. Since there is no life present in the container to consume Ca, the only explaination is that the chemical reactions have completed and the water has become more stable. Letting your water circulate, aerate, and age a few days prior to use allows the water to come to an equilibrium. An equilirium between dissolved oxygen and carbon dioxide levels as well as all of the other internal chemical reactions taking place within the salt mix. Newly mixed saltwater is far more corrosive and caustic than aged water and that can be hard on equipment as well as your live stock.


I think many people would agree with most of this. This sort of 'premixing' -- letting freshly mixed sw sit for a while (24 hours is a common recommendation) -- has its benefits, as mgustin points out. Note that this is not the sense of 'premixing' whereby a person puts tank water into the premix (as mgustin points out in the rest of his post that I've snipped from).

mgustin, do you have any evidence (chemical and/or anecdotal) for the last claim in the above passage: "Newly mixed saltwater is far more corrosive and caustic than aged water..."? This seems a bit contrary to what you said regarding the KH of SW actually decreasing slightly with age; everything else being equal, that would make the pH of newly mixed SW higher than that of aged SW.

[mgustin]

I think many people would agree with most of this. This sort of 'premixing' -- letting freshly mixed sw sit for a while (24 hours is a common recommendation) -- has its benefits, as mgustin points out. Note that this is not the sense of 'premixing' whereby a person puts tank water into the premix (as mgustin points out in the rest of his post that I've snipped from).

mgustin, do you have any evidence (chemical and/or anecdotal) for the last claim in the above passage: "Newly mixed saltwater is far more corrosive and caustic than aged water..."? This seems a bit contrary to what you said regarding the KH of SW actually decreasing slightly with age; everything else being equal, that would make the pH of newly mixed SW higher than that of aged SW.

Have read such in many articles concerning mixing synthetic salts. Took it as fact based on the sources. I do not have any scientific experimental results to post for you.

My post did not say dKh would decrease. I posted that Ca may decrease while dKh increases given time to come to equilibrium. This all really depends on the source water used. If you use RO/DI water but do not aerate first to drive off CO2, you will end up with a lower pH and dKh in the mix because the CO2 will consume the buffers and cause the end result to be lower.

[mgustin]

Here is some support to the claim that newly mixed saltwater is caustic.

http://kb.marinedepot.com/article.aspx?id=10779

Excerpt:

Mixing Saltwater


Correctly mixing saltwater for a marine or reef aquarium is a vitally important—yet relatively easy—task.

First, find a container that can hold (at least) 5 to 10 percent of the volume of water used to fill your “display” tank. Old aquariums and clean garbage cans are popular among hobbyists, but you can choose whatever works best for your own “mixing tank.”

Next, fill the container with dechlorinated or reverse osmosis (RO) freshwater.


Add synthetic salt, being careful to follow the manufacturer’s instructions so you can match the salinity of your mixing tank water to your aquarium water. Ideally, salinity should be 27 to 35 parts per thousand (ppt), or 1.020 to 1.026 specific gravity. Use a refractometer to measure salinity and adjust your level accordingly.

Freshly prepared synthetic seawater is very caustic (capable of burning or corroding), so it will need some time to “cure” before it can be used in your aquarium.
Allow the newly mixed seawater to sit in your container for a minimum of 24 hours before use. During that time, place an airstone or powerhead in the water to circulate and aerate the mixture. Lastly, drop in a heater to match the water temperature to that of your display tank.

[68551]

John, why do you question how harsh newly mixed saltwater is??? Wether you answer on forum or just to yourself ....Would YOU put your prize coral or fish in newly mixed saltwater without diluting it in your tank??? I don't know many into saltwater tanks that would!! I believe Fenners advice makes sense for just that reason!!!!

[Daniel Reef]

I'm getting back into the hobby soon and at the very least I have learned that I need to premix the salt and let it stand for at least 24 hours. If anything, that is very helpful to know.