This has probably been the worst week of fish keeping I've ever had since I was getting started with the hobby over 5 years ago. I've lost 5 Apistogramma Nijsseni, 4 Corydora Sterbai, and 10 cardinal tetras. I believe it's due to my wildly swinging pH, but I don't know for sure.
So let me paint the picture for you and see if you have any advice.
72 Gallon bowfront tank with a 29 gallon sump. My setup thread is here: (link)
As you can see, I had two large rock piles in the tank and two decent sized pieces of driftwood. I'm not sure exactly what kind of rock it is, because I gathered it from my in-laws' property, but it doesn't look like limestone. My substrate is a mixture of play sand and pool filter sand from Lowes.
My tap water is a bit high out of the tap (8+)
Week 1: Set up the tank and let water run through it to bleed some tannins out of the driftwood.
Week 2,3: 100% Water change (no fish yet) let some more tannins bleed out.
Week 4: Shipment arrives. Use Seachem acid buffer to bring the pH to 6.9, add some Prime to make sure Chlorine / Chloramine is out, add two decent size rocks from already established aquarium to the sump as a bacteria start.
I also added a large amount of live plants.
livestock at this point includes 5 Apisto Nijsseni, 2 Gold Rams, 6 Amano Shrimp, and 6 Nerite Snails
My excited picture post is here (link)
Week 5 : Very light feedings and nightly Ammonia / Nitrite checks. Weekly doses of Seachem Flourish and Flourish Excel. I had a small, barely measurable nitrite spike for two days, but never saw any ammonia. Fish are doing fantastic.
*FIRST MISTAKE*: I didn't do frequent checks of pH, so I have no idea if that was rising or not.
Week 6: Light feedings, doses of Flourish and Flourish Excel, everything is still going well.
*SECOND MISTAKE*: I stopped testing things, so I have no idea what was going on with my water here.
Week 7: 40% water change, I used Seachem acid buffer to bring down the pH of the water I was adding to match the 6.9 I assumed the tank was still at. (It couldn't rise that high in two weeks, right??)
Did a pH test at the end of the water change, and the tank was at 7.0, so I thought I was doing good.
Week 8,9: Everything is sailing along smoothly, or at least I think so because I don't notice any problems.
Week 10: Another 40% water change. Used the same mix of acid buffer to keep the pH of the water down around 6.9.
Week 11: Got another shipment of fish, added 12 Cardinal Tetras and 6 Sterbai Cories. Throughout the week, I lost exactly 1 cardinal a day, and I found one dead Sterbai. At first I thought it was just an acclimation problem with the Sterbai, and possibly a feeding issue with the tetras. (They weren't handling the full sized brine shrimp or NLS i was feeding).
*THIRD MISTAKE* -- Should have tested the water again here.
Week 12 (thjs week): Did another water change, same as before, and measured the pH at 6.9 afterwards.
On Tuesday night, I had lost another cardinal, so I was down to 8, and one of my apistos was looking a little pale. I tested the water, and my pH was at 8, so I added a little bit of acid buffer and went to sleep.
Wednesday morning, most of my apistos looked a bit unhealthy, and my cories weren't as active as normal. I was in a rush so I just left.
I came home to a disaster. All of my apistos were dead, two of my cories were dead, and another was gasping his way out. I was also down to 4 cardinals.
I tested the pH again here, and it was at 8.5.
Here's where I'm most confused. If everything was going well before, what would cause my pH to spike so high so quickly?
I couldn't think of anything that could bring my pH up so quickly except for my rocks, so I pulled them all out. It was a really sad experience scooping up all of those dead fish.
This evening, I had lost 1 more cardinal tetra, but everything else was holding strong. My pH went up to 8.7 though even without any rocks in the tank!!
So my big questions are:
1) What is killing my fish? I would think it's the pH swings, but it could be just how high the pH is. It could also be something completely different. I tested my water again today, and I have no Ammonia, No Nitrites and scarcely measurable Nitrates. I thought about heavy metal poisoning from the rocks, but I would think that would have killed the shrimp and snails (They're magically ok). Could it be an illness? Is the high pH a red herring?
2) Why does my pH keep going up, even without rocks? My only guess right now is that the Acid buffer from Seachem claims to turn alkalinity into CO2. If my plants use up all of that resulting CO2, does it turn back into alkalinity as a by product? I don't know the chemistry behind how plants use CO2.
3) What would you all recommend for me? If the buffering product is the problem, I can try to find some Peat or other material to bring the pH down. Are my plants causing a problem? Do I need to install a CO2 system to keep my pH down and the plants happy?
This is my first SA tank, and my first fully planted tank, and it's not going well at all so far. Any help at all would be greatly appreciated.
I've done pretty well with Malawi and Victoria cichlids, and have done a bit of successful breeding, so I thought this would be a great step up for me. Maybe I wasn't quite ready yet....