Kalkwasser Questions

[luv951]

I have newly set up reef; 6 months old or so. 90 Gallon Display, 175Gallons total system. Not too high of calcium requirement yet - five or six SPS, couple Zoas, few shrooms, frogspawn and hammerhead. Also, the cleanup crew is in, couple hundred snails, 50 or so hermits.

After reasearching and reading a few articles from Randy Holmes-Farley, I would like to start dosing Kalkwasser with my top off. The top off is automated.

My questions:

1.) Current Alk is 8 | Current Calcium is 340 | Ph is 8.0. Do I need to bring these levels up using separate supliments (as per BRS' starter kit) or can I just start dosing the kalkwasser?

2.) Water changes. Currently I take water from my top-off reservior and gravity feed it to my mixing reservior. I then drain the tank and pump the new salt water in. This won't work with kalkwasser, right? I can't use kalkwasser for water changes since it would add too much and raise my Ph too much as well as might cause a precipitation event, right?

[disc1]

1) I would bump the calcium up a little first. Kalk isn't good for raising levels, just maintenance.

2) You are correct. You wouldn't want to do that.

[ecomdesign]

1. I would raise your calcium to 420-450. My understanding is that kalkwasser works best when alkalinity and calcium are more balanced. Also beware that magnesium isn't supplemented by kalkwasser. You will want to check mag and correct it as well. The good news is mag doesn't need to be doses as often. Once everything checks out, then start your kalk.

2. You cannot use kalkwasser water for water changes. Only clean rodi and salt.

How to you plan to add the kalkwasser to the tank? Do you plan to add it throughout all hours of the day? Or only durin lights out?

[ecomdesign]

LOL-you beat me while I was typing...

[luv951]

I have been letting the tank top-off whenever it needs it, but recently decided to put my top off on a timer so that it only tops off for certain interval per day. That way, my solenoid and pump are not switching quite so frequently. once the kalkwasser is added, I would top off at night, when the Ph is lower.

So, do I need to raise my alk too?

The BRS Starter kit has stuff to raise the Calc and alk...

http://www.bulkreefsupply.com/store/kalkwasser-starter-package.html

Is this a good choice to begin this process?

[ecomdesign]

That kit contains sodium bicarbonate which is gernally used in tanks that run at a ph of 8.4 or so. I guess they offer sodium bicarbonate with this kit due to the idea that your tank will start to run at a little high ph then 8.0 on kalkwasser?

I'm not sure how fast you current pump adds top off but kalkwasser must be added slowly. I use a litermeter3 dosing pump.

[luv951]

Its a tom's aqualifter.

[luv951]

is that going to be OK?

[ecomdesign]

Yep. :) as long as it' slow as possible. Many people use toms aqua litters for kalk.

[luv951]

I don't know about as slow as possible, but it sure is slow. Takes half hour to an hour to replenish the water usually...it is pretty much one step faster than a drip, but certainly not a good stream.

So is the BRS starter kit a good way to go?

[bertoni]

The starter package should be fine. :)

[luv951]

OK, thanks guys

[luv951]

Aother question:

I have read that you should not dissolve kalkwasser into saltwater, for several reasons, not the least of which is you would be topping off with saltwater.

But, what if there is a little bit of left over salt in the water?

The best way I can figure to make this work with my setup is to re-purpose my water change tank (15 Gal.) into a kalk tank. My F/W top off would then become a w/c tank, but would also be a F/W reservior from which I would periodically fill the kalk tank so I could mix the solution. After I do a water change, there would be a bit of salt left in the tank, residual water, etc...would that small an amount make a difference the kalkwasser?

[ecomdesign]

Don't think it's a good idea to have salt in it but maybe someone else can confirm. Do you plan to use a lid on the kalk tank? The more sealed the better. I use a 5gal screw top instant ocean bucket for my kalkwasser.

[Randy Holmes-Farley]

There cannot be any appreciable salt in the limewater. Any magnesium will precipitate as magnesium hydroxide, depleting both the magnesium and the alkalinity.

Tiny traces are ok. :)

[luv951]

So, if its a 15 gallon tank with say 1/4 inch or less (.3 Gallons) of 1.024sg saltwater in it and I added another 10 gallons of fresh on top of it, could I get away with that?

[Bretts05jeep]

Just tagging, lots of good info I will be needing in the near future.

[Randy Holmes-Farley]

0.3 gallons will have about 1.5 grams (617 millimoles) of magnesium in it. That is enough to totally deplete 30 liters (8 gallons) of limewater.

So no, that isn't ok.

[luv951]

Wow, thanks Randy.

Guess I had better come up with a redesign of my system here. Shoot.

[Randy Holmes-Farley]

You could just wipe it out with a towel. :)

[luv951]

What if I was to use a kalkwasser reactor instead? I know that there are disadvantages to that, but before I even look at those, I need a better understanding of the process I would use. Is it:

Kalkwasser reactor on the edge of my F/W reservior. When the auto top-off signals to fill the tank, rather than just activate my aqualifter, it would activate a powerhead that would drive the F/W through the reactor, with the outlet from the reactor leading to my sump?

Is that about right?

[Randy Holmes-Farley]

That is roughly how they work, yes. :)

[luv951]

Thanks again, Randy. I think I figured this out.

I am going to Tee off my RO/DI feed, so that by turning some valves, I can direct the flow from my top-off res. (which will have kalkwasser in it) to my S/W changing res. That way, i can fill both with RO/DI as needed.

This way, I only need to buy another top off controller and I can dose the kalkwasser in the preferred method with my top-off.

Thanks for all the help everyone, its greatly appreciated.

[tmz]

The Tom's aqualifter is spec'd at .22 liters per minute; but, they vary in performance . Dosing fully sturated kalk to a 15 gallon tank at that rate for very long,more than 30/40 seconds worth per hour, will likely overdose. From your earlier post it's not pushing limewater that fast in your set up ;but, dosing all of the top with fully saturated limewater off in 30 minutes is still problematic. Your daily top off at say 1% would only be about .57 liters If you are using fully saturated kalk for top off ,dosing it in 4 or 5 increments at least one hour apart helps avoid ph spikes and precipitation of calcium carbonate which often occurs when to much is dosed at once.

[luv951]

not sure I follow you. My main system is about 160-175 gallons (depending on displacement from live rock, etc.) Thats 600 liters, easily.

If I dose at .22 liters per minute, in an hour, I would dose 13.2 liters, or about 2.2% of my tank. Are you telling me that this is too much for the tank?

I am not sure if maybe you misunderstand that I have a 15gal. display....

[bertoni]

I think that rate should be fine for the display. If you're dosing into a sump or the like, the flow needs to be high enough that the sump doesn't get overdosed.

[luv951]

That makes sense. Thanks!

[bertoni]

You're welcome! Good luck!

[tmz]

I did misread your tank size;missed it in the first post. Sorry for the confusion.

13.2 liters is 3.5 gallons which is 7tsps of kalk at full stauration(2tsps per gallon). That much dosed in an hour to 175 gallons may spike ph. The max safe level recommended to avoid raising ph unpredictably by Sprung and Delbeek in "The Reef Aquarium Vol 3",pg 217 is 1/4 tsp of kalk powder per 50 gallons per dose with each dose at least an hour apart which would be .875tsps pr hour for 175 gallons or about .44 gallons of lime water @2tsps per gallon or /1.66liters per hourly dose.So if the aqua lifter is delivering .22liters per minute ,running it about 7.5 minutes per hourly dose would work within the recommended level. The pump may do less or more depending on how it's installed( head loss, etc) and it's quality . Measuring the output would be prudent.

This article by Randy H Farley has a lot of useful information on kalk and kalk dosing:

http://reefkeeping.com/issues/2005-01/rhf/index.php#12




This is from it:
" The fact that limewater is very basic (the pH is typically above 12) demands that the limewater be added slowly to an aquarium unless very small additions are made. The reason for this is two-fold: to prevent the local pH in the area of the addition from rising too high (slow addition permits more rapid mixing with tank water to reduce the pH), and to prevent the overall tank pH from rising too high (slow addition allows the tank to pull in CO2 from the atmosphere during the slow addition, mitigating the pH rise)..."

[luv951]

Great article. I had actually already read it. The issue is that "slow" is a very relative term, as it would need to be given the article's broad audience. Your above post makes sense. My top off is automated, so all that's needed to create a situation of slow addition is to set up a timer that only allows it to fill for say 5 minutes, every couple hours.

I was going to add a timer anyhow to provider another layer of protection in case my redundant floats fail. This is just a programming issue at this point and you have made it very clear (thanks!) why I should go with a several-times-daily program.

I appreciate your efforts to put numbers to your statements. Very helpful.

[Randy Holmes-Farley]

The slower the better on limewater addition. Spreading the daily evaporation out over many hours is optimal.

Adding 1.25% of the water volume as limewater at once will boost the pH by 0.6-0.7 pH units or so. That is too much, IMO.

That applies to a sump as well, although if flow through the sump is high, sweeping the limewater away before it has a chance to cause precipitation, then you may be able to add 1% or more of the sump volume over a few minutes without a substantial problem.

[tmz]

You are welcome. Randy's 1.25% = 0.6 to 0 .7 ph units is very clear way of expressing the issue . I couldn't recall it and was looking for it in my notes but couldn't find it.

A timer is what I had in mind and should work for you . The added advantage of incremental dosing over a long period of time as top off is a bit more constant salinity.

Consistency may be an issue with the Tom's aqualifter. I use those pumps for moving small amounts of water ,in seahorse fry set ups for example, and have no problem with them. The precision of amounts of water moved are less critical in those applications and there is no heavy calcium carbonate concentration to clog them.It may work just fine for lime water but I'd measure the output from time to time. I've used a peristaltic pump with a built in timer for 24/7 lime water dosing for several years with good results.

Good luck.

[ecomdesign]

Thanks for posting that article. I haven't read it in 2 years and I got a lot back out of it. I was under the misconception that it started to degrade in my covered pail after a week. I also clean the bottom of my bucket at ever refill. I'm going to get a larger container for my kalkwasser as my pail only lasts 4 days.

Sorry for the highjack-thanks for posting and thankyou Randy for writing it! ;)

[tmz]

You are welcome .

I run mine from a 32 gallon brute can. It will hold it's strength for weeks in a still(unstirred) reservoir.

[luv951]

I think a good place to start would be to measure the output of my Tom's, and also figure out how much evap I have each day - although I know that figure will vary greatly with time of year and ambient humidity, etc.

I will take both Randy's and TMZ's advice and put a timer on the top-off. I am thinking of starting out with it running every two hours for about 5-10 minutes. I will feed into the point in my sump where the overflow from my display meets the outflow from my refuge tank and also my skimmer outflow. Very turbulent right there. Recall that its a 75 gallon sump.

From my calcs, I figure if I turn it on every two hours, I can replace 3.48 to 7.96 gallons of water in each 24 hour period, assuming my Tom's is running at full strength. I doubt that I evap that much in a day, so I probably have the option of slowing that down considerably.

Its all just math though, so some measurements are in order.

Once again, thanks to all who took the time to post.

[petedoc]

I am trying out a simple Kalkwasser reactor device, a simple 10" clear filter housing with a tube running to the bottom from the intake and kalk in the bottom 2". I run RO/DI through it for about 10 minutes twice daily. The system is sealed eliminating air exposure, except for the output tubing. The output must remain above the water otherwise backflow occurs and precipitation results. I would be interest Randy Holmes-Fairley commenting on this system.

[boatguy]

I have another question...If it is bad to pump too much kalk at once and you already have an auto top off running...the would it be OK to use a lot less lime in your water? Say 3 tsps in 5 gallons?

[tmz]

Yes using less is fine. It's the amount of lime entering the tank that you wan't to control either by diluting it to a lower saturation or reducing the amount of liquid dosed. For a generally safe dose, 1/4 tsp of the calcium hydroxide per 50 gallons of tank water per hour has been recommended , however it's diluted with fresheater : 1/4 tsp per gallon or even less or two tsps per gallon or anything in between.

[antjtc]

Yes using less is fine. It's the amount of lime entering the tank that you wan't to control either by diluting it to a lower saturation or reducing the amount of liquid dosed. For a generally safe dose, 1/4 tsp of the calcium hydroxide per 50 gallons of tank water per hour has been recommended , however it's diluted with fresheater : 1/4 tsp per gallon or even less or two tsps per gallon or anything in between.

If my ato pumps in 5 cups of RO/DI water all at once, once a day, what would be a safe amount of calcium hydroxide to put in my ato reservoir if I want to add x amount to a gallon of ato water? My aquarium volume is 80 gallons. If someone could figure out a starting dose x/gallon as well as max safe x/gallon I could gradually increase to if necessary I'd appreciate it. I have my ato pump set to a timer to pump in ato water for one minute, once a day. The amount it pumps in is very close to 5 cups. Let's also assume all my ALK and Cal levels are where I want them to be and the limewater is meant to maintain my current levels. Thanks

[Randy Holmes-Farley]

"safe" depends on where it is going.

If it rapidly mixes into the whole tank, then you can add about 0.1 or possibly 0.2% of the tank water volume all at once using saturated limewater (2 teaspoons per gallon). If you add 1% of the volume, that solid added would drop from 2 teaspoons per gallon to 0.2 teaspoons per gallon of fresh water.

But if you add to a sump and the water is there for a bit before mixing in, the same calculation applies to the sump volume. maybe double it, but more than that and you risk a lot of precipitation in that sump.

[tmz]

Sorry, I did misread it for a 15 gallon tank.

However, 2.2% of water volume in fully saturated kalk per hour is still too much for a 160 gallon. Randy calculated a 1.25% of water volume( a more common top off need than 2.2%) fully saturated kalk addition would bump ph by 0.6 to 0.7 units which is too much. So with the amount planed, 2.2% , the ph boost would be about to 1.25 units ,say 7.8 to 9.05 . A ph spike north of 8.5 is likely to cause precipitation.

Slow dosing over as long a period of time as possible , generally at least 4 to 5 hours for a 1.25% top off is realtively safe . This allows time for CO2 from the air to eqilibriate with the water at a rate consistent with the limewater's effect in depleting it.