ORP fluctuations with water changes negatively affecting corals

[jlinzmaier]

Hello.

I have a 200 mg Red Sea ozonizer and typically the ORP of my tank reads about 330-340. I have approx 200 gal total water in my system so I do 30 gal water changes approx every 10 days. When I do the water changes my ORP drops suddenly from 330 down to about 260. I guess I would expect this as the new water I'm introducing isn't oxidized yet, however, some of my corals react negatively due to the sudden drop in ORP. My elegance coral shrivels up and retracts all tentacles until the orp begins to get back up to around 300-310.

Does anyone else have this problem??

Other than hooking up an ozonizer to oxidize my freshly mixed water, does anyone have any other suggestions?? (My current ozone reactor set up isn't very mobile so I'd need to purchase a new ozonizer and build a new reactor.)

Any suggestions would be greatly appreciated.

Jeremy

[Billybeau1]

I do not believe the reactions of your corals is being caused by a drop in ORP.

Freshly mixed salt water has an ORP of about 220 - 240 mv and a drop is to be expected when doing a water change.

A 15 % water change is not a lot. I think your corals reaction has more to do with HOW you do your water change.

It could be the sudden loss of water flow, the temperature of the new water, could be a number of things.

If your schedule does not permit you to do smaller more frequent changes, then I'd pay real close attention to the temperature and the salinity of the water you add. Maybe add it slower. :)

[Randy Holmes-Farley]

I agree that they are almost certainly not responding to ORP. They may be responding to something else in the new water, good , bad, or otherwise. Corals often expand more when water changes are performed, for reasons that I am not sure of.

All the ORP reflects is the relative balance of the oxidation states of certain metals like manganese and iron. I have no reason to believe a coral knows about or cares about ORP per se.

[jlinzmaier]

Thanks for the feedback Billybeau and Randy.

When I do water changes I match the salinity and temp so I'm pretty sure that's not the problem.

When I change the water, I vaccuum out the detritus on the bottom of the display and I have a float valve that automatically tops off the sump with the new water. There are no changes in the water flow and or filtration as I'm performing the water changes. Not sure what the problem is but I'm glad to hear you don't think it's related to the change in ORP.

I'll investigate further.

Thanks for your input.

Jeremy

[m2434]

I would guess something along the lines of a small ammonia spike. New salt water may contain excess ammonia and stirring up the sand bed may lead to even more...

[Randy Holmes-Farley]

Stirring up the sand may also irritate them.

[jlinzmaier]

It's a bare bottom tank and I vacuum out all visible accumulations of detritus when I do my water changes. For the most part I don't disturb much other than what gets sucked up and discarded.

In case there is a possibility of having ammonia or any other toxins in my freshly mixed water, I'll try running a bit of carbon for a few hours in my mixing reservoir before I add the water to my display.

Jeremy

[Billybeau1]

<a href=showthread.php?s=&postid=12350981#post12350981 target=_blank>Originally posted</a> by m2434
I would guess something along the lines of a small ammonia spike. New salt water may contain excess ammonia and stirring up the sand bed may lead to even more...

I do not believe ammonia is your problem. I know of no salt mixes that add ammonia to our systems.

Maybe just try going slower on the water change. :)

[Randy Holmes-Farley]

Maybe try a different mix and see if the effect is the same. :)

What mix are you using now?

Some salt mixes do have some ammonia in them, but not usually enough to impact anything in a normal water change. :)

[jlinzmaier]

Since I spend time vacuuming detritus from the bottom of the tank, my water changes take me about 20-25 min. Changing out 30 gal of water over 20-25 min in a 200 gal system certainly wouldn't be too fast. When the freshly mixed water is added it also mixes with the other water in the sump before it even enters the display.

I'm using Tropic Marine Salt. I switched from IO to Tropic Marine about 6mo ago after I found out IO had some batches of significantly low calcium and magnesium (lost faith in IO).

For the most part, most of the corals seem fine with the water changes. My big beautiful elegance coral just seems to react so negatively it made me concerned. The elegance didn't always do this with the water changes and truly I can't remember when I started noticing the reactions. Maybe I've got a bad batch of salt or something odd like that. I'll order some new Tropic Marine and another brand of salt and see if I notice the same reaction. I've had 30 gal of freshly mixed water ready to go in the tank and last night I made a contraption to utilize the powerhead to continuously filter the water through about 1/2 cup of carbon. It seems ridiculous to have to filter freshly mixed water, but I'll see if it make a difference. The carbon will have been in for about 12-18 hrs by the time I do the water change and that should be plenty of time to pull out any incidental organic toxins.

Really appreciate everyone's advice and input. I'll keep you updated.

Jeremy

[Randy Holmes-Farley]

after I found out IO had some batches of significantly low calcium and magnesium (lost faith in IO).

Do you mean Reef Crystals? Regular IO has always been low. :)

Good luck and let us know what you find! :)

[jlinzmaier]

Sorry should have clarified - I meant Reef Crystals. A large batch went out with ca lvls of around 300.

[Randy Holmes-Farley]

Ah, yes, I have some of those by mistake where I meant to hit the IO order button, but got that instead. :D

[jlinzmaier]

Guess I should also clarify that I use Tropic Marine Pro Reef, not just Tropic Marine.

I'm thinking I'll order Red Sea salt mix and see what kind of results I get.

Will keep providing updates.

Thanks everyone.

Jeremy

[jlinzmaier]

Randy and Billybeau.

How often do you guys clean your mixing resevoir??

I don't ususally scrub and dry my container becuase as soon as I do a water change I usually fill it up with RO/DI water and add salt right away (I like to have it on stand by in case I need to do an emergent water change). I continually aerate the water with an air stone and I have a powerhead that runs continuously so the water is never stagnant, but I guess it's been about 3-4 mo since I've cleaned and dried my mixing bin. I wonder if there is some residual organics that were incidentally introduced or something from the water that has built up and been been causing my problems. I would think that freshly mixed water should be clean and free of any organics that could eventually break down and cause problems but maybe I'm wrong.

Just a thought.

Jeremy

[Randy Holmes-Farley]

The salt mixing reservoir? Almost never. Here's what mine looks like:

What is that Precipitate in My Reef Aquarium?
http://reefkeeping.com/issues/2005-07/rhf/index.htm

from it:

http://www.reefkeeping.com/issues/2005-07/rhf/images/Figure_1.jpg

Figure 1. The residue on the bottom of the plastic trash can that I use to mix Instant Ocean. I rarely clean it out. The solid is most likely calcium carbonate.

[Billybeau1]

:lol:

I don't clean mine but once a year or so. Mine doesn't look quite like Randy's. :D

I do not think that is your problem either. But keep thinking. You'll figure it out. :)

[mhaith]

Just a flyer here but you keep saying freshly mixed salt water. Are you always letting it mix for at least 24 hours or so before using?

[jlinzmaier]

mhaith

Yes. I ususally mix it for several days before I use it. As soon as I do a water change I fill the mixing resevoir again with RO/DI water and add the salt. It usually mixes for at least a week before being used.

Jeremy

[jlinzmaier]

After I used carbon to filter some freshly mixed water in which I used tropic marine salt, none of the corals showed a negative reaction.

Bought some Red sea salt mix and used it with the next water change (about 4 days later) and the corals seemed to show a healthy extension of polyps and a more positive reaction to the water change.

Not sure what's going on, but I guess I'll switch to red sea salt mix and assume there was some impurity or bit of ammonia in my tropic marine salt mix. Not saying all tropic marine mix is bad but maybe I got a bad batch or something. Corals seemed to show a more positive reaction with the red sea mix so I guess it's worth switching (cheaper too!).

I'll chalk it up as a bit of a mystery resolved by switching to a different salt mix.

Thanks for your input everyone.

Jeremy

[Billybeau1]

Jeremy, there is certainly something to say for changing salt mixes,

I am of the opinion that if it looks good, it is good. If you like the way your tank looks with the new salt mix, stay with it.

Everyones tank has different needs. :)