I've been getting this odd brown muck on my 9 month old tank.
It is covering virtually all the surfaces and falls off the plants when I
touch it. It feels slimy.

Is it nitrifying bacteria or diatoms?

See pictures please.

http://mytriops.com/temp/whatisit.jpg
http://mytriops.com/temp/whatisit2.jpg

Tank is pretty loaded with fish unfortunately.

I had a ramshorn explosion and I took someone's advice and added snail
killer chemicals...duh....
So of course I got an ammonia spike due to the dead snails.
The ph of the tank is 6.4 @ 22C so not too lethal and I'm doing water
changes. But this damn stuff keeps coming back.

I would have said it was diatoms, mixed in with bits of detritis that have stuck to it.. sure is alot though.

Thank you for that.

I did a 200% water change yesterday with me rubbing the stuff off the leaves. It's all back 24hours later covering everything.

All the leaves closer to the light definitely have more of this stuff on them.

My Corys in the tank are courting like crazy...

I'm at a loss at what to do about the diatoms.

Does it wipe off easily? I've got a 10g with lots of tiny snails in it. I find I get lots of brown fluffy mulm that settles out on everything without a strong current across it.

It seems like it shows up overnight (when snails can be active) so I'm pretty sure it's due to the snails because I don't see it in any other tanks.

Doesn't really bother me much unless I fall behind in my water changes.

If it wipes off realtively easy but feels a little greasy then diatoms are a logical assumption.

For diatoms I've found that a few ottos will take care of it quickly. It seems to be their favorite food.

Try and fluff it off as best you can, doing water changes to get rid of it and addinf a bit more CO2 will help.

F F- got it right.

You can try a 2 day blackout + Excel + Water changes each day(no CO2 during this time).

Add more filtration perhaps also, prune some biomass back, clean well aftrer you do any large changes in the tank(water changes, filters etc)

Regards,
Tom Barr

Bartman - Yes it wipes off very easily. I can't put in otos as the tank is already at maximum capacity. Ok if its diatoms then I can get to grips with it.

Tom - Thanks Tom, I've ordered some Excel and I'll give your advice a try.

Frolicsome_Flora got it right.
Good news, it's easy to get rid etc, bad news, you have some cleaning and perhaps adding a filter in there as well.

Regards,
Tom Barr

I'd thought I'd follow up with my experience.

I did a large 100% water change, switched off the lights and covered the tank with some large sheets of black cardboard (I knew they would come in handy one day!) and added a old 2nd internal filter I had lying around.

I added Stability every day and 2x dosage of Excel on the 2nd day and left it for 3 days.

After the 3rd day I removed the sheets and switched the lights back on.
The tank looked ok. I did a large water change and removed any damaged or algae touched leaves. I fed the fish.

On the 4th day we had our 1st sunny day of the year. The temperature in the tank rose from its more usual 22-24C to 27C. I put on a large fan next to the tank to try to reduce the temp.

But I got up on the next morning to find 6 dead fish. 4 corys were dead and 2 zebra loaches. I also found one of my Dwarf African Frogs had escaped and died all dried up.

I did water tests.
Ammonia 0
Nitrite 2ppm
Nitrate 5ppm
ph 6.4 (usual)
GH < 3dh
KH very low 3d or lower

My clown pleco and golden bristlenose were still alive.
The white cloud mountain minnows and glowlight tetras were almost unaffected. Just sitting low in the tank that day.

I added a dosage of Prime to get rid of the toxic nitrite. But it was only 2ppm and the tank was aerated throughout and the surface did have some water movement due to the filter.

I did the tests using Tetratest sticks and a API freshwater master test kit.

No diatoms.. But at quite a cost.... I really liked my zebra loaches...

Yesterday I tried to feed the 2 last corys and zebra loach and they're just not in the mood. probably all stressed out.

This morning their behaviour is looking a bit more normal.

I guess I'll never know why the fish died on mass. ph shift perhaps or something toxic from the old inserted filter?

What is "Stability"? I always suspect it is something I added when I see a problem, so I rarely add anything except fertilizer and CO2.

Excel:
1x is enough/plenty, no need for 2x, which killed the fish.
50-80% would have been fine for a WC.
Not 100%.

I think some folks got a bit crazed with Excel and in their impatience, suggested to folks with BBA or Hair algae to bomb the plants at the sake of the fish's health.

Excel will kill your fish and I think that's more than likely when combined with the 100% daily water changes, the temp might have helped, but was not the entire story.

Regards,
Tom Barr