Skewed ammonia readings?

[BeansMom]

New member! My little warrior Smarty is nearly recovered from a horrible case of Fin and Body Rot (among other things) . He is in a 2.5 gal tank which is filtered, aerated and heated to 79 degrees. He is in 100% spring water with a 25% water change done every 2 days, and a gravel vac of about 20% once a week. He is fed (for the week) HB pellets 2-3 twice a day, a meal or two of FD Bloodworms, a meal of BettaMin flakes. He doesn't appear to be overfed (has a perfectly rounded belly per my research). He is near the end of his second round of Melafix. Even after yesterday's gravel vac, his ammonia readings come back high. With all the water changes and the mini power filter, how is this possible?? Can the Melafix cause a skewed ammonia reading? He does not appear to have any symptoms of stress from ammonia or otherwise (he is one happy, fiesty little guy!)

[amanichen]

There's a number of things which can cause "false" ammonia readings. The first is how the test kits work. Some test kits only detect ammonia "free ammonia," while others detect ammonia and ammonium "total ammonia."

Basically, when ammonia is dissolved in water, you get this happening:

NH3 + H2O <=> NH4 + OH

Most of the ammonia that's formed will get turned into ammonium, but some of it stays as ammonia.

The NH3 (ammonia) is pretty dangerous while the NH4 (ammonium) is pretty innocuous. Now, if you want to know how much of a threat the water is to your fish, you want to look at the ammonia level only, and not the total combined level of ammonia and ammonium. If your test kit only does total ammonia, you'll have to find a conversion chart based on temperature and pH to see the actual NH3 level.

A second source of error in this are products which make ammonia non-toxic for fish. Amquel is an example of this, and ammonia which has been "neutralized" still shows up on some types of ammonia tests.



Now, as for the ammonia levels being high after a water change...I offer the following explanation. If we go back to this chemical reaction:

NH3 + H2O <=> NH4 + OH

We'll see that there's a double arrow there. That double arrow signifies that the reaction can go both ways, but eventually it'll reach an equilibrium, where the reaction is happening forwards and backwards at the same rate. If you disrupt that, by say, removing ammonia from the water, then you'll cause some of the NH4 and OH to form back into ammonia and water.

A water change alone shouldn't affect this -- since you're removing equal proportions of each chemical. The thing that might, is if your water conditioner removes ammonia, then some of the NH4 will break back up into NH3 to take it's place.

Remember that the fish, and heterotrophic bacteria in the fish's habitat are constantly excreting ammonia. If your water changes aren't enough to keep up with it, then the reading still might be high.

Your filter might also not yet have a large enough colony of nitrifying bacteria on it to deal with all the ammonia in the environment. If the tank has only been running for a couple weeks, this is to be expected.

[Rachel]

Hi BeansMom. Happy to see you posting and glad to hear that Smarty is continuing to improve!

I have nothing to add to Amanichen's post, lol, but just wanted to wish the best of luck to Smarty for a full recovery. You've been doing a great job so far!

[BeansMom]

Thank you both for such complete explanations! You are right, his filter medium is new (I removed the carbon while treating for the Fin Rot). My ammonia test kit is by Jungle - if my memory serves me correctly (I am at work...shame on me), it does test for a combined ammonia level. I will definately check that when I get home. My tank is about 6 weeks old, and your instincts are absolutely right on - I have added ammonia "stoppers". It has been a long journey for my little guy and I want to be sure that everything is exactly right. I also have a 5-in-1 test kit by Mardel that I have been monitoring the PH and other water properties with...my tap water is VERY HARD, so I've been putting the spring water disributors in fat city for a while. I will put all of your suggestions to work and let you know how it reads! Thanks so much

[amanichen]

I was afraid it would fly over your head, but now I'm relieved to know that you understood it =)

[BeansMom]

I am printing our your post to use for reference while I look for a test kit that will give me what I need. It's wonderful to have good information (we all know how good the info at the pet stores is, don't we?)

[amanichen]

BeansMom said:

(we all know how good the info at the pet stores is, don't we?)

There's a topic over in "general chit chat" about pet store employees. I think it's pretty representative about how people feel about them =)