When to "blow up" a tank

[jodilynn]

Hey all,

I figured that this would be the best place to get some advice regarding an old tank I am having some problems with.

It is an old 10 gallon tank that I just keep a few C. sterbei, an L144, a few platies, some God-awful "fighting loach" and a betta in. It was my son's first "real" tank and has been running undisturbed (other than the actual tank being swapped out when it leaked) for about 8 years.

Undergravel filter, dual sponge filter, Marina HOB (rated for 20 gallon) with a sponge, biological media, and filter cartridges (those are changed every 6 weeks). Weekly water changes 20-50%. Temp 78.

Water parameters:
Nitrate: 40 (need to do water change cuz of COURSE I missed this weekend due to a hockey tournament)
Chlorine: 0 (well)
Hardness: 300
Nitrite: 0
Alkalinity: 300
Ph: 7.8
I have not checked the ammonia lately but when I do there is none.

Now this is the problem. The platies and bettas (and I have also tried Rams, both sunset and dwarf gouramis, and various other fish) shrivel up and die shortly after being introduced. A couple months at the longest. They seem to get a very heavy white film on them (not a fungus or ick or fuzz, almost like their slime coat is thickened), and just waste away. They eat till the bitter end and just die.

I have tried Pimafix, Melafix, Paraguard, Metroplex, Kanaplex, Focus mixed with both, salt, higher temps...nothing works and nothing saves these fish . I have lost three really nice bettas and while platies aren't anything special I don't buy fish to kill them . My platies that were born here in other tanks are just fine and I have had platies for years in other tanks with no issues.

The corys are fine but occassionally flash a bit. The pleco I never see but when I shine a flashlight on him at night he looks fine. And the weirdest thing is the baby platy that was born in that tank is just fine.

Took the water to the LFS multiple times to be tested with the master kit and they say it tests absolutely fine.

I am at the point where I have a spare tank open and am contemplating taking my survivors out and just tearing the tank down. Hot water and Oxyclean on all gravel and decor and pitching all the sponges and filter media. Washing the inside of the tank out with vinegar. And starting over .

Any thoughts? I have 14 other tanks and no issues, including another 10 gallon right below it running the same setup (different fish).

I am just clueless...

[Viktor Jarikov]

Josh from Ohio Fish Rescue recently gave me a valuable advice. If a health problem persists in a tank / system, do a thorough vacuum and clean out of all waste, debris, silt, crud, etc. (just don't wipe every surface where BBs live but rinse the biomedia), and then reapply the medication. If tank uncycles a bit, add Ammolock until it gets back.

I imagine there is a LOT of detritus in the under gravel filter. It'd also be a good time to chuck it too. I've never used them as I read lots of bad things about them.

[jodilynn]

Honest Viktor I can see underneath the tank and there is little to no sediment under there.

I have been using UGFs for 35 years. I guess old habits die hard? Those are the only filters in a few of my betta show tanks.

[Viktor Jarikov]

Sure, some people like them and they work fine for them. Overall, the hobby forsook the UGF. I suppose you are able to somehow keep the underneath clean or the detritus is stopped and accumulated in the substrate, which you vacuum.

But overall, the advice of Josh is experience-based. When meds can't eradicate a persistent problem, it's time for a major clean.

[Jools]

Odd one this but maybe it's too clean. There's a lot of filtration and medication going in there. I am also not sure what a fighting loach is? I used u/g filters for years and they're perfectly good if you have large sized gravel and "hoover" it from time to time. Most other types of filtration are just simpler to run especially for beginners. However, you have the other filtration in there, so you could just pull out the uplift and switch the air to an airstone.

Post a few pics or video of the tank?

Jools