Rapid Ph Flecuations

finchfarm

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As many of you know, we had to recycle our tank. While the tank was cycling our water was a consistent 8.6 or so. Once the tank finished cycling our pH dropped down to 6.0 which is no big deal since we keep Amazonian fish.

However, a few weeks after our tank got cycled we had a problem with our pH dropping. We went to our local LFS and the owner told us to stop using Topfin Dechlorinator as this was bumping down our pH. He sold us Prime instead and said that it would help boost the pH along with dechlorinating our tap water. He even showed us a water test where he'd done a pH reading, then put the Prime in and the color in the vile changed. We stopped using our Topfin and used the Prime instead and the pH started going up.

But now we're having a problem with rapid pH flectuations. We went on vacation a few weeks ago and were gone for six days. The pH in the tank was 6.5 when we left. I left instructions for my father on how to take care of the tank and when we came back home the water was at 5.0 in just six days and all the new fish we had just bought were dead. I cleaned the tank and did some partial water changes and got the tank back up to 6.0.....three days later and its down to 5.5. As said, I know pH falls overtime, but I thought this was unusual so I went back to the same LFS as the first time.

We talked to a lady this time and she said that offentimes pH and ammonia are intertwined. We had an ammonia testing kit but its at least 10 years and probably expired so we bought a new one. I tested the ammonia this afternoon, followed the directions in the pamphlet and let it sit for 20 minutes for the colors to change. The test kit said there was no ammonia.

I really don't know where to go. I've been doing partial water changes whenever the pH starts to drop, the tank is gravel vaced at least once a week, the filter is efficent, there's no ammonia, the fish finish eating their food within 5-10 minutes. No one can seem to find why our pH is so low, or why it drops so rapidly.

As stated, I have Amazonian fish, but I'd like the pH to be between 6.0 and 7.0, not 5.0. Our fish that we have now can tolerate the rapid flectuations, but any new fish we get dies.

Any ideas on what might be causing the rapid flecuations in pH and how to fix it?
 
My pH kept dropping in spite of regular water changes. It turned out that my carbonate harness (kH) was low. The LFS tested my kH, saw that it was low and told me it is a common problem in our area. You can buy tablets to put in your tank which dissolve overnight. I had to do this for 6 nights, and keep an eye on my pH as these tablets raised the pH which needed to be reduced at times. If my pH starts to drop again, I'll be getting my kH tested again. Hope that helps.
 
Yeah your tank has no Carbonate Hardness as Branjie stated.

This is a ph crash, and is when an older tank starts dropping rapidly in ph due to very low carbonate hardness. Carbonate Hardness is what keeps your ph stbale. No matter how many water changes you do, if your carbonate hardness is not raised your ph will continue to crash.

The causes that contribute to low carbonate hardness all relate to adding to much CO2 into your tank, such things as:

Very mature bacteria (more bacteria means more CO2 exhaled)
CO2 Kits (a direct source of CO2)
Overstocking (more CO2 exhaled)

...these issues should be addressed before you start experimenting with the ph as first the carbonate hardness needs to fixed before a ph will stablise.

If any of the information above is incorrect then someone please correct me.

...
 
I've never really tested kH before, only a few times, so I'm not sure what everything means. My test kit said the test is complete when the water in the tube turns a from blue to a bright yellow. The first drop turned immediate yellow but then went to clear, when I put in a second drop it stayed a pale yellow. I also tested our tap KH.

Tank kH: 1-2 dkh? (not sure since test never turned blue)
Tap KH: 3 dkh (definite blue-to-yellow color change)

Humm that's interesting, I don't think there's overly mature bacteria, though could I be wrong even though the tank has only been set up for a few months? I haven't used any C02 kits and to my knowledge I don't think I'm overstocked....so I guess my quetions now are, assuming I have a kH problem......

1. Can I have too mature of bacteria even though my tank has only been set up for a few months.

2. Is my tank overstocked? It is 75 gallons (2 feet wide, by two feet tall by about 4.5 to 5 feet long). In it I have one full grown Red Hook, two baby Silver Dollars (about 2-3 inches long), 5 Zebra Danios, 1 Marble hatchetfish, 1 Angelfish (about 3 inches long), 1 Black Skirt Tetra (about 2 inches), one brown ghost knife (about 3-4 inches), and one small Sailfin Pleco (about 4 inches). I've asked about this stocking before and everyone said I was fine and didn't have to worry about being overstocked.
 
The problem is your water has a very low buffering capability which means the PH can fluctuate a lot in a short space of time.

I cant remeber the science off the top of my head (someone will be able to explain it) but basically the lower the KH of the water the easier it is for other factors to change the PH. The higher the KH the more "immune" it is to PH changes. ideally you want it around 5dKH (degrees) to keep the PH stable. Lower then this and very slight changes in CO2 Levels or other ph altering factors can rapidly change the PH a lot.

Example (not using the proper maths):
Water with a KH of 2 has 2ppm of CO2 added, The PH swings from 7 down to 6
Water with a KH of 8 has 2ppm of CO2 added, the PH swings from 7 down to 6.9

The actually numbers will be different but this is just to show you.

What you need is something to buffer the KH. I cant recommend any products I'm afraid but I'm sure there are plenty out there (bicarbonate of soda?? Dont just use this but can anyone confirm?)

I actually have the opposite problem where I live in that my water is very hard so I have to lower the KH (my KH is about 14dKH from the tap if I remeber correctly).

Small changes in PH are normal by the way. Mine changes around 0.2-0.3 during the course of the day.
 
Yeah, I'm almost pretty much certain that's what the problem is.

I won't be able to go to the LFS this weekend, so in the meantime I'm keeping a pH diary of sorts monitoring everything I'm doing. I've also read a few articles on KH harness on the web. As soon as I get the chance I'll probably be making another trip down to the LFS to see what they can sell me in the way of water hardening stuff.

Tanks gonna make me go broke. -_-
 
you can add very small amounts of pure baking soda to raise ph. however, someone told me that raising the ph so suddenly (even if by only 0.3) is not good for the fish.

i have had problems with declining ph for a long time now, and i am finally looking into possible solutions that do not require continual adding of baking soda once or twice a week.

i hear that small amounts of limestone or crushed coral in your filter can raise kh and therefore ph as well. if using either, make sure to put it in a small pouch or fragments might get into the filter impeller.
 
Looks like I'm getting a reading of 0.1 in ammonia too. I gravel vaced the tank and did a partial water change yesterday and now this. Any thoughts?
 

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