Milky slime

[Ladyindiana]

My tank has this slimy milk-colored sludge along the bottom. It is nearly impossible to "vacuum" it up. It's either very dense or stuck to the bottom. I have found a few threads that talk about it, but none that have my same parameters.

I have a 55gal freshwater. I have 9 tetras, 3 danios, 1 kuhli loach and an upside down cat. No real plants though. 4 days ago I switched over to a Fluval U4 and do have an air stone that is 1/2 the length of my tank. My tank has been set up for over 3yrs and has never had this problem.

Ammonia 0
Nitrate 200+
Nitrite 0
Total hardness 150
Total alkalinity 0
pH 6.2

I've NEVER had high nitrate! And my nitrite has NEVER been 0. The numbers have exactly flipped! I battle high nitrites and acidic water constantly. Even with 30-60% water changes. Now I have an opposite problem!

From what I've read it sounds like I'm going through a cycle but I'm very concerned about my fish with the nitrates being so high. Obviously I want the slime gone, but the nitrates really concern me.

What is the recommended procedure to safely lower the nitrates and clear the slime while keeping the fish healthy?

 

[Byron]

From the photo, it looks like uneaten fish food bits that have fungused, in part anyway. I would siphon out as much as you can, and reduce feeding. Only feed what actually gets eaten in a few seconds.

As for the nitrates, this would be comparable with uneaten food, and other things too. Assuming there are no nitrates in your tap water (have you tested it alone?) do several major water changes (I would do 50-60% ofg the tank volume, maybe even more if your tap water parameters are close to the tank parameters), vacuuming into the substrate; cleaning the filter might also be needed. Nitrates within the aquarium can occur from too many fish (too large, or too many), overfeeding, insufficient water changes, and organics accumulating in the substrate (or elsewhere) and the filter. Live plants also help, though this can be quite limiting...but that leads to the issue of fertilizers; too much can contribute as well.

There is no benefit in "slowly" lowering nitrates, the sooner you can eliminate as much as possible the better. Many inaccurately consider nitrate "safe," but it is not; ammonia and nitrite are more quickly acting to poison fish, but nitrate can do the same if the concentration is high or prolonged or both. Different fish species have differing tolerance for nitrate, but keeping it as low as possible, and always under 20 ppm, is wise. Over time it weakens fish, leading to other issues.

Byron.