daxton wrote: ↑Thu Jul 17, 2025 3:46 pm
Based on what you've said, I think the plants are the culprit behind your tank's dramatic pH drop - 1 point in just 2 days is a big change. What's your tank's stocking like? I'm guessing the fish aren't too thrilled about the situation right now. If I were you, I'd remove the plants ASAP. Real plants do help with nitrate levels, and in an ideal setup, they can even bring nitrate levels down to zero. However, they're not the best choice for a Mbuna tank, as these fish love to dig and will likely end up eating the plants. If you want a similar look without the hassle, consider using silk plants instead. I've got a few in my Mbuna tank, and they look pretty realistic without causing any water issues.
Your advice was on the money, mate, plants can indeed impact pH levels. They're constantly removing and adding CO2 and O2 to the tank, which has a slight effect on pH. And let's not forget about dead leaves contributing to waste in the tank, making it more acidic. But for such a drastic pH change, I think there's more to it than just the plants. KH and GH play a massive part in keeping the pH stable, and I think that's a big factor here.
I personally think he'll need to buffer his tap water once this issue is sorted, as 7.6 is a bit low for a rift tank. But first things first, we need to figure out what caused the crash in the first place.
I was just trying to help out, but in hindsight, I should have considered the possibility of a KH/GH issue, especially given the drastic pH drop over a short period. I didn't ask about the tank's setup or running time, nor did I inquire about the water parameters. Old tank syndrome is a possibility, and I should have explored that avenue further before offering my initial advice.
Dead plants aren't a significant source of ammonia compared to other types of waste. For them to have a substantial impact on CO2 levels, you'd essentially need a tank overcrowded with plants, leaving little room for fish. Even then, it's unlikely they'd cause a pH drop. If plants could produce enough CO2 to cause such a drastic pH decrease, there'd be no need for CO2 injection in planted tanks.
However, assuming plants did cause the pH to crash due to high CO2 levels, you'd expect the pH to return to normal the following day after the lights were on for a while. The plants would've used up the excess CO2, and water surface movement would've eliminated any remaining CO2, causing the pH to rise back to its normal 7.6. This isn't the case here, according to the OP's information. pH fluctuations caused by CO2 levels have minimal impact on fish, as they're unrelated to the water's softness or acidity in terms of mineral content, GH, and KH.
Hi everyone, thanks for all the advice. I didn't know things were so serious when I started this thread. I've got some more info that might help.
There were 6 plants, but I got rid of them yesterday. No big deal, I can replace them today.
TANK INFORMATION
Tank's 3 months old, 330 litres but with the 3D background and ocean rock, it's more like 300 litres.
Filtration's an external filter, 2000 LH.
Powerhead's a Hydor Koflakeioa Evolution 2800.
Heater's a 300w heater, keeps the tank at a constant 25 degrees.
I've got 17 juvenile mbuna cichlids, all look healthy and acting normally. Very little aggression, fish seem fine.
I've been doing 20% water changes every week, including sand vacuuming and cleaning the filter.
Feeding's been 2 or 3 times a day, takes about 2 or 3 minutes for the fish to clear it all. I know now this is way too much. I've read I should feed them once a day and the food should be gone in a minute. I'll do this from now on.
TEST RESULTS ON DEC 27th
pH 6.0
Nitrate 5.00
Nitrite 0.00
Ammonia 0.00
TEST RESULTS ON DEC 29th
pH 7.6
Nitrate 5.00
Nitrite 0.00
Ammonia 0.00
I don't get how my pH went from 6 to 7.6 in a couple of days. No water change, just removed the plants. The fish should be stressed, right? But they look and act fine. I'm hoping it's just the overfeeding. I'll wait for confirmation from you guys. I love my tank and I'm worried my fish might be unwell with the pH all over the place.
Thanks again for all your posts, I'd be lost without this forum!
You mentioned "garden centre" - that got me thinking, were the plants you added actually aquatic plants? I've heard of people buying non-aquatic plants by mistake, even from fish stores. Do garden centres in your area sell aquarium-safe plants? I'm curious, what kind of plants were they? Hopefully someone with more plant expertise will chime in soon to help you figure things out.
