What Causes Ph Crashes?

[This Younger Spouse]

[font="arial][size="2"]Hey all:

First of all, please excuse the typo in the header. I coulda sworn I typed in pH.

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[font="arial][size="2"]I'm interested in what causes pH crashes.[/size][/font]

I posted one today in the Fish Emergencies Forum, and got answers that will help me for the coming days, but I need to nail down the root of the problem instead of continuing to treat the symptoms.

A week ago, after taming an ammonia spike, my readings were:

pH 6.6
Ammonia 0.0
Nitrite 0.0
Nitrate 10-15

These are typical reading for this tank, and our tap water always tests around pH 6.5/6.6. Then we dumped our old API Master Kit because we'd realized the chemicals had expired a year earlier, and were without a kit for about a week until we picked up the Nutrafin (Hagen) kit today.

And my readings in this 55-gallon tank had gone to:

pH 5.0
Ammonia .6 mg/L (which based on the ammonia toxicity chart on the back of the test pamphlet indicated was 0 toxicity).
Nitrite 0.0
Nitrate 5 ppm

To verify the precision of our new Nutrafin kit, I tested a couple other things. Our tap water tested at 6.5, as did my 20-gallon tank.

In my fully cycled 55-gallon, I've had for several weeks two small firemouths, two small Jack Dempseys (yeah, don't bother scolding me for that. I know, I know. I'm trying to rehome some of them!), one BN pleco and one Synodontis cat. A few weeks ago I added quite a few aquatic plants, some from my spouse's tanks and some from the LFS. There are now 9 healthy plant clusters in the tank. The substrate is silica sand and quartzite gravel. The rocks are quartz and basalt. There is one chunk of well worn freshwater driftwood about the size of a boot.

My ammonia spike we've attributed to overfeeding (cichlids are messy eaters and I don't want to underfeed juveniles) and some of the plants melting away a bit due to transition. I did daily 70-90 percent water changes to control the ammonia spike, and everyone seemed to be playing well together in the tank after that. I've got about 22 inches of mostly juvenile fish in a 55-gallon tank, and the bioload seems plenty small.

I was very careful to thoroughly read and follow all the directions on the Nutrafin kit, which was new to me. I also tested pH in the tank twice, from different parts of the tank.

 

[Caprichoso]

This article may be of help to you.

http/www.bestfish.com/oldtank.html

Good luck!

 

[coldcazzie]

For the record, I had similar issues with test kits, which is why I don't use them much now. The API pH test kit always showed 6.4 tank pH, nutrafin showed 5. The problem is that the kits are not very accurate. I doubt your tank has actually plummeted pH-wise in the space of a few days, especially after a week of daily water changes which will have nicely buffered your water. I'd chalk it up to different test kits.

Personally, I can't remember the last time I tested my pH. Ammonia etc were last tested...whenever it was I added 17 fish at the same time. Before that I can't even remember.

Also, Caprichoso, how can he have ots after several daily water changes? Ots requires several months of no water changes, organic waste buildup and nitrate so high they are off the chart. I accept that the nitrate kit is at best, unreliable, but nowhere does he say my nitrate is high, or "I've been ignoring my tank for the last year" or anything similar.

 

[StandbySetting]

What's your KH?

 

[This Younger Spouse]

I've posted KH in the other emergency thread. It was 20 yesterday and 30-35 ppm this morning after a night of filtering with 2 tblspoons of crushed coral. pH tested about 5.3 or 5.4 this morning. I've also read about the unreliability of pH tests, but it struck me that a change of 6.6 to 5 is more than an order of magnitude, and that seemed to be quite a lot for me not to try to take some action. I used the API test strips to get a KH level, and the test strip showed a pH a bit above 5 as well.

Um, honestly, we'd for sure pay $100 USD for a kit that was dependable and accurate. If you can't rely on a kit, why buy one? I know the financial realities of profit margin and cost of materials and manufacture, and that the margin for error is somewhere in the neighborhood of +/- 10 percent. At what point does a kit become useless? It seems it could actually cause more harm than good, rushing into attempts to change a tank's chemical levels when they may not in fact be elevated.

I'm especially struck by coldcazzie's experiences with her API and Nutrafin test kits essentially duplicating my experience.

I should add that our tap water has always tested about pH 6.5 or 6.6, and the Nutrafin test kit put tapwater pH at 6.5 last night, with my 20-gallon tank also testing at 6.5. I'd be more comfortable dismissing the pH test on the 55 but for this.

I'll be out most of the day today, and will greet this thread with great interest upon my return.

Thanks for the help so far.

 

[This Younger Spouse]

Just tested. No change in KH or pH from this morning. Starting WCs in the morning, if it's even worth it. Probably just another tempest in a teapot.

 

[This Younger Spouse]

This morning, pH and KH in the 55 remained unchanged at 5.3 and 30-35 ppm, respectively. The 20-gallon, in contrast, has a pH of 6.5 and KH of 80 ppm.