rough week for my fish?

[cm12setx]

I have lost 2 cardinal tetras one Sunday I put it down had a growth for the last three weeks. and added 3 rummy nose tetras but I did acclimate them right lost one Sunday night and one Monday morning. than the 2nd cardinal tetra Tuesday, and finally today i lost both black neon tetras. the water parameters have been 0 ppm ammonia every day 0 nitrites. and 10-20 ppm nitrates. on Sunday early afternoon wc 5 gal on a 20 gal tank. and have done 2 gal wc Mon, Tues, Wed, and 5 gal today. Ph is 7.4-7.6 . the only other thing I have done is added some plants. two weeks ago I added koato and Echinodorus Argentinensis -- Argentine Sword. Yesterday I added Staurogyne repen and Cryptocoryne. do you all have any ideas. thanks

[mnemenoi]

what is your temp? Both are finicky species and can be problematic

[cm12setx]

Temp is 82 deg F. Had the cardinals over year and a half. Rummys were added on sunday. Black neon were six months at least.

[cm12setx]

Lost lost the last rummy today. Looking for.idaes of.what went wrong

[mnemenoi]

Rummy Nosed tetras dislike hard water and always seem to be problematic, the temp appears to be good, Black Neons are usually bullet proof, so I'm not certain exactly what happened. Can you describe the tank in detail, all your specs and parameters you know. Might help me spot any issue I might see.

[cm12setx]

water temp 82 F; Ph is 7.4-7.6 ; GH unknown i an not sure how well this test works KH 7 Deg it changed after 7 drops with api liquid test. The test expired late last year. ; ammonia .25 ppm, nitrite 0 ppm, nitrate 5 ppm the ammonia might be up the last rummy died sometime on Friday and did not find him till 630pm under IAL : ammonia usually 0ppm nitrite 0ppm nitrate 10-20 ppm

This tank 20 gal long. This tank has been running for 1 year and half. Weekly wc of 5gal.
20watts t12 24" plant aquarium light
1 1/2 IAL, 4 pieces driftwood
AC 30 hob filter
small air pump with air stone.
Plants: all added with in the last two weeks.
1.Echinodorus Argentinensis -- Argentine Sword
2. Staurogyne repen
3.Cryptocoryne
4. my opps koato

Stock: was 4 cardinal tetras, 4 glowlight tetras , 2 black neon tetras, 2 GBRs, 2 green laser corys, 1 albino cory, 3 otos.
In the last month lost female GBR 3 weeks ago, 1 cardinal put down due to weird growth, than Sunday picked up 4 rummy nose tetras, 2 albino corys. Sunday lost 1 rummy it never settled in , Monday lost 2nd rummy looked ok, 3rd rummy on Tuesday it looked ok, Wednesday lost both black neon tetras and they looked good no issues, Thursday no issues , Friday lost the last rummy and did not find it for a while. I don't see aggression issues from Male GBR. the first 2 rummys might have been rushed acclimation.
As it stands 4 glowlight tetras, 2 cardinal tetras, 1 GBR, 2 green laser corys,3 oto,3 albino corys.

on the black neons that day I moved the air stone from the 20 to my 5 late in the evening and when I got home after work the next day found both black neons dead. "wounder if they died from lack of oxygen over night?" but i dont think so.
Am I missing anything eles to help with info on this tank?

[cm12setx]

just ck ammonia 0 ppm this morning.

[mnemenoi]

Hmm, have you tried testing your tap water for Ammonia? It has been an issue here in Houston before. The removal of the air stone should not have caused any oxygen deficiency, but does sound like Ammonia issues. Plants seem fine, no issues there and likely cause of Nitrate reduction. AC30 should give enough surface agitation, are you seeing a strongly restricted water flow rate? GH/KH/Ph and parameters look good other then the Ammonia reading and its a bit high. I can only chop it up to that, otherwise tank looks great. Its really weird for a tank to show any reading and be a year old. It suggests a ton is going in, as the bacteria consume it quickly. Dead fish can be the cause, but one rummy in a 20 gallon with a filter should not even register or be a trace. I have a sneaky suspicion it might be an additive to the tap water. The water company can add things occasionally and remove them as well, so its a variable thing that might have been an issue when you water changed it. Now it might be gone. Check just in case and see if you get a hit. Prime will take care of it until the bacteria break it down. Ammonia readings can also be a sign of Chloramines (which should be taken care of as well, but we are hunting something weird so..) Just guessing here and looking under every stone as it were. It sounds like you do a terrific job, hate to see when even us aquarists are baffled. I'll keep pondering and see what else I can come up with....

[cm12setx]

cool thanks I do need to recheck the tap water. doh I have ck it for ph but not Ammonia. your help is really appreciated.
On a side note my five gal my EBR got POPeye again. I think it was from swimming into something. but the nitrate was 20-30 ppm I did several wc in this tank 2 gal at a time and now the eye looks good.

[mnemenoi]

No sweat always happy to help, wish I was a bit more helpful. I always like a mystery though and it feels great to finally find the solution.

[cm12setx]

well with time it gets better. I think I will leave well enough alone till the end of the month to let every thing settle. I still want to add frogbit to the tank. and look for Pygmy Chain Sword (Echinodorus tenellus. but this will be later.

[cm12setx]

mnemenoi checked my tap water this morning. ammonia 0 ppm.

[mnemenoi]

Hmmm, it was a long shot anyways. I'll keep thinking, might just have to check it out in person lol. I'll be going through Beaumont to get to and from work in the next few months...

[cm12setx]

Shoot me a.pm and let me know if you are in the are or when.

[mnemenoi]

Shall do, It will be another month at least. After that I'll be flying out of Intracoastal City La.