Corys dying, Tertras acting weird, Hard water and High Nitrates

[mbrum]

I have a 20 gallon tank with 1 honey gourami, 2 red eye balloon tetras, 3 neon tetras, 1 remaining cory cat. All has been well for many months with weekly water changes and an under gravel filter.

Last week a snail died, this week I lost a cory cat and for last 2 days remaining cory cat has been lethargic, occasionally swimming to surface, and hiding. Other fish are also huddling in corners and acting strange.
Today I did a 30% water change and suctioned gravel, I also added a new canister filter because I want to gradually switch over from UGF so I can grow more plants. Fish seem more stressed now. Maybe due to water change or to increased water flow with 2 filters running.

Tested water and found some problems: nitrites 0, nitrates between 40-80 ppms (Yikes!), ph 7.5, KH 80 and GH 180 (too hard I think). Temp is about 76 degrees.

I would appreciate any advice about how to deal with water quality issues. I would also appreciate any insights into issue with cory cat. Thanks

 

[shellieca]

I have a 20 gallon tank with 1 honey gourami, 2 red eye balloon tetras, 3 neon tetras, 1 remaining cory cat. All has been well for many months with weekly water changes and an under gravel filter.

Last week a snail died, this week I lost a cory cat and for last 2 days remaining cory cat has been lethargic, occasionally swimming to surface, and hiding. Other fish are also huddling in corners and acting strange.
Today I did a 30% water change and suctioned gravel, I also added a new canister filter because I want to gradually switch over from UGF so I can grow more plants. Fish seem more stressed now. Maybe due to water change or to increased water flow with 2 filters running.

Tested water and found some problems: nitrites 0, nitrates between 40-80 ppms (Yikes!), ph 7.5, KH 80 and GH 180 (too hard I think). Temp is about 76 degrees.

I would appreciate any advice about how to deal with water quality issues. I would also appreciate any insights into issue with cory cat. Thanks

I would do a 50% water change & then retest, if nitrates are still 40 or higher do another 50% water change. Some say nitrates need to be less than 20, others less than 40. What was your ammonia? Ph of 7.6 is fine. Sorry can't give input on the Cory's.

 

[mbrum]

I haven't tested ammonia. I'm going to buy more test strips tomorrow. Maybe that could be the problem.

 

[Ljk09]

Are you using test strips for everything? Test strips are extremely inaccurate. I'd invest in a drip test. They're about $30. How long has your tank been running? Do you know if its cycled?

 

[Coco1019]

Instead of test strips, I would advise getting the API Master Test Kit. It's a bit more money up front, but less in the long run and a lot more accurate.

 

[shellieca]

I haven't tested ammonia. I'm going to buy more test strips tomorrow. Maybe that could be the problem.

Any things possible? If at all possible get a liquid test kit, more expensive up front but saves money in the long run & much more accurate.

 

[mbrum]

The tank has been running for about 8 months, pretty sure it has cycled. Maybe I'll get a better test kit to see more clearly what's going on.

 

[clearancepuppy]

You will never want to go back to strips once you have that test kit. That is the most dead-on accurate awesome tool in your arsenal. Without it, you are wandering around in the dark with a very weak flashlight.

Cories in my experience are some of the most durable fish there are. They are also very sensitive to high nitrates. I also think snail deaths are telling you to get this under control now with API testing kit and 50% pw changes until your nitrates aren't off the charts.

I would get some Prime as well. Start doing the water changes ASAP. The prime is also a bit expensive but a little goes a long way. Throw one capful into the new water.

Side note: have you been adding salt? If you've
dumped aquarium salt in without diluting it or added too much, the salt can burn a Cory up.

 

[Dreadz]

Running ugf and canister at the same time isn't really a good as idea as the ugf will be fighting against what the canister is trying to do - remove waste from the tank.
I would take some gravel and put it in a filter bag in your new filter and switch off the ugf. Do some major PWC's and at the same time give your gravel a really good deep vac to remove all the decomposing matter that will have accumulated in the gravel bed and that should help to solve the nitrate problem. You may start a mini cycle but test every day for a week or two with the liquid test kit and do PWC's if your ammo or nitrite pass .25 or .5 and you should be fine.