What else to do before starting over
I have a huge mystery going on where I am unable to keep any fish alive, for more than two weeks, in all new 55gal tank. Before giving me the nitrogen cycle, your a newbie, standard answers, note I have raised fish for over 20 years. This post will be long but going to try to cover all the items and history with this tank. Looking for any last ideas before I shut this tank down and start all over.
* 55gal SeaClear Acrylic Tank
* Aquaclear 70 filter -- two foam blocks and the bag of the biomedia that comes with it on top
* Fluval 250W heater
* Airpump and airstone.
* Black sand from Petco
* Several rocks from a previous tank that I have used for years.
* One new white rock from aquarium store, looks like coral but isn't (can't tell you what it is but came out of a cardboard box buried under some shelves)
* A few new plastic plants
* Two live plants left in their plastic containers.
* API Master Water testing kit.
My water source:
* Local city water. It tends to run at pH 7.6-7.8. Does sometimes smell like Chlorine. Area is a high limestone area and most of the city water comes from wells. Water seems to have a high Calcium (but I can't test that but have seen the results in my shower).
My method for adding water:
* Adjust bathtub faucet water to 78ish degrees. Fill two 5gal buckets.
* Treat water with Seachem Prime and stir in.
* Use a smaller 1gallon pitcher to slowly add water to tank. Once the Lowes bucket is light enough, I lift and add the rest of the water. It typically takes me about 5-8min to get 10gal added to the tank.
My method for adding fish:
* Remove water and fish from plastic bag into a 1gal plastic pitcher (the one used for adding water).
* Use airline with a knot to drip acclimate from my tank into pitcher.
* Make sure I don't fill the pitcher or go more than 1/2 new added water in less than 30min
* Once 3/4 my water to 1/4 fish store water, I move the pitcher into the tank and use it's handle to keep the pitcher from sinking into the tank.
* Typically takes an hour for the temperature to equalize
* Net each fish, one at a time, and into the tank they go.
Tank has been up now for a solid five months. When I got this new ClearSea tank, it came in a plastic bag. It washed the tank out really well but has never had a drop of soap in it. After two months of fish dieing, I stopped adding fish and did a fishless nitrogen cycle using pure ammonia (took forever to find but Tractor Supply Company has it) using a popular method posted on here and many websites. The cycling took 22 days and I plotted all the results in a spreadsheet. The ammonia and nitrites cycled as expected and big water change at the end brought nitrates back down. At the end, I could raise the tank's ammonia to 4.0ppm and it would be back to 0ppm within 24hrs. The plants seem to be soaking up some of the nitrates because nitrates never went above 20-40ppm.
During the fishless cycle, brown algae set in. We took out the white coral-like rock because we didn't want to have to scrub it. Left the other plants in there. Once we were done, scrubbed the remaining rocks and put them back in the tank. We left the brown algae on the plastic plants.
We have been focused on mollies and platies. After the big cycle at the end of the fishless cycle, we added six Dalmatian mollies. One was pregnant. For 3 days, ammonia remained 0. Finally gave them a touch of food and momma gave birth to babies overnight. Ammonia was at 0.5 in the AM, Day 4. I did a 20gal water change before work, tested ammonia again and I was back in the 0.25ppm, no feeding for Day 6. When I got home from work on Day 7, the ammonia was back to 0. Nitrites never left 0ppm, Nitrates came up to 5ppm. Unfortunately, the babies were not in a breeder net and the mollies ate most of them, and the first molly was dead. For the next two days, I lost one molly per day. Meanwhile the ammonia never went above 0.25ppm and was either 0 or up just a touch.
When we got down to three Dalmation mollies (now at day 10), we added three Platies. I tested the store water to find their ammonia to be 1.0ppm. Mine was 0. Got them added to the tank (per my method above) and everyone was doing well again. At Day 12, I fed them and everyone went nuts for food. Then, one more molly died on day 13, and then next molly died on Day 14. The three Platies and the one remaining Dalmation were doing really well.
Two days ago, the last Dalmation died and one of the Platies died yesterday. The remaining two Platies just swim at the top and show signs of ammonia poisoning. I've tested the water every day for the past seven days and ammonia, nitrites, and nitrates have been 0ppm. I even compared tap water vs tank water in two tubes and cannot see a color difference.
Saturday, I pulled another 10gal (25ish% water change), no effect. Today, ammonia at 0ppm, Nitrities 0ppm, and Nitrates almost 0ppm (just up alittle but not enough to be 5ppm). Last two remaining platies are at the top just breathing heavily. I forecast at least one of them to be dead by morning despite it's been 3 days back at 0ppm Ammonia
Random other notes:
At one point before I did the fishless cycle, we wanted to see if we could keep even one Betta alive in this tank. She started showing unhealthy signs and stopped eating after only 3 days in the tank. We pulled her out and put her in a glass jar with freshly-treated tap water. Within a few days, she started eating again and she is beautiful now. That's what pushed me to do the fishless cycle.
My next steps:
Yesterday, I got out an old 10gal tank that I used 10+years ago for a "new babies" tank. I have set it up repeating my steps I did with the 55gal. Except, I'm using the heater, filter, and gravel that already went with the 10gal tank. I'm going to add a couple fish to it and see what happens. If the fish live there, then I know it's specific to the 55gal tank. If the fish die, then I know it's either something with my city tap water or my process.
* What other chemicals could be present that would result in fish showing the same behavior as ammonia poisoning?
* Was there a prep step with acrylic over glass that I didn't do? I just rinsed it out real good nad moved on.
* Could chemipure elite possibly get out whatever this chemical is?
* The Fluval Heater keeps temperature spot on but could it be bad sending current through the water that would give the fish "ammonia posioning look"?
* Is it possible the sand is "bad"?
IF I decide to tear down the tank and start over, is there anything I can do with the sand? Like bleach bath it? Or should I trash the sand and start over? Or what if I let it completely dry out for several days?
What about washing the filter? Should I wash the foam out with bleach and then restart a nitrogen cycle .. just in case?
Any thoughts, insights, or recommendations...I'm all ears!
Thank you ahead of time!