Why did my PH drop ?

[iskatefast]

My tank has been very stable. I have never measured (and still don't) any ammonia. The Ph has always been right around 7.0 . Last night I noticed a little cloudiness and decided to do some test. The pH was off the charts on the low side. All the fish seem fine and everybody is eating. I do feed a little more than I should because the peacocks are machines!!! I feed all the pleco's a variety of flake, blood worms, prawns, and cucumber. The peacocks and gar get goldfish a couple times a week.
I recently added phosx . Other than that , everything is the same as always. I have my water tested regularly and pH has never been an issue. I did a water change last night and re-tested but pH was still way too low! HELP!

[ferret]

Check the hardness level (gh/kh). Too low and you can have a 'ph crash' .. I don't know too much about it but its a place to start.

[BrianNY]

Hi iskatefast. I'm curious about the size of your tank and not only what kind of filter you have, but what your using in it, and how often you clean the filter. My gut feeling is that if you're using any sort of carbon, it has absorbed all it can and is now releasing back into your tank.

[madasafish]

Welcome to the site!

So many things could be going wrong here. And you're right to be worried about the pH as Malawi Peacocks (i.e. Aulonocara spp.--I assume this is what you mean by "peacocks") and gars (which species? needlenose? Alligator?) need a pH above 7.

Why did you add phosx? Generally FW aquarium ppl don't mess with or even monitor phosphorous levels (thought pond ppl sometimes do)... Was it because you were worried about algae in the tank?

And, water cloudiness often indicates a bacterial bloom (if it's gray) or an algal bloom (if it's green). Either way, you're going to want to get rid of it. I can certainly help you on the algal problem, and can probably advise you how to get rid of the bacteria.

Until then, if you're most interested in getting your pH back up, I'd advise you to consider the Seachem range of pH buffers. "Neutral Regulator" will keep the pH at 7, while some higher pH products by Seachem such as "Lakes Malawi and Victoria Buffer" (name is something like that) will keep your pH at 8 or higher. Since it sounds like you might have a buffering crisis (i.e. carbonate shortage) in your tank, you should think about gradually introducing backing soda to the tank. But I'll let someone else tackle the buffering question, as I'm no expert...

[jsoong]

OK. I'll take up the buffering bit.

In simple terms ... The water you first put in your tank contains minerals, one of which is HCO3- (bicarbonate), which happens to be the main buffer in FW system. H+ (hydrogen ions = acid) reacts with the HCO3- to make CO2 (which escapes the tank). As long as you have HCO3- in your tank, it will eat up any H+ produced, and your pH won't change (much). BTW, when there is a shortage of H+, the buffer system can also gives off H+, so your pH won't rise much either.

The problem is that as H+ is produced, the HCO3- gets used up. When it is all gone, you have no buffer left, and any H+ produced will remain, thus your pH drops or crashes ... bad for fish.

Where did the H+ came from? The fish. Fish produces ammonia (NH3). When the NH3 is converted to NO2 then NO3, H+ is released. Plus, fish also produce various organic acids as waste.

That is one more reason to do regualar partial water changes, to replenish your buffers, and to get rid of other wastes.

[Robo]

jsoong, that was a great explanation.

does anyone know what the average pH is of fish waste? human urine is around 5.0 since it has a high concentration of the organic acid urate (uric acid).

[madasafish]

I think human urine is supposed to have a higher pH than that... 6.5 or so. Though it certainly can be lower. A friend of mine has a kidney stone, so this has come up

I don't think fish waste will change the pH too much unless you have huge fish...

[BrianNY]

Jsoong, that's an excellent technical explaination of what is probably occuring. Thanks for that analysis.

He's got large fish, feeds very messy live foods (gars eating goldfish are very sloppy). I think the amount of waste produced in this tank begs for a diligent chemical filtration. In your opinion, besides waer changes, don't you think that carbon changes should be done often?

[sweetsuvvyb]

Additionally, phosphates can act as an additional buffer (similar to the carbonates) in a tank, and by using a product that removes them, you can alter the buffering capacity of your tank, and cause a pH crash.

Because of it's recent addition correlating with your pH problems, I'd guess that's what caused the problems.