[brmatt1022]

Hey all,
A few weeks back I had a sudden mulm build up. Within a week my tank went from looking great and vibrant green to now mulm building up on all the plants. I’ve been doing water changes and rinsing my filters in the old water but it hasn’t slowed down. Now, I’ve lost 4 fish (3 glowlight tetras and 1 h rasbora) in a matter of about 6 days. I tested my water: PH at. 6.5 (I know that’s low buts it’s been consistent), Ammonia at a 0, Nitrite at 0, and Nitrates between 25-40. I’ve tried to think back to any changes but I can’t think of anything out of the norm. Any ideas on what could be causing the deaths and mulm build up?

 

[brmatt1022]

Here’s a before the mulm and after the mulm pictures

 

[ichthyogeek]

How large of water changes have you been doing?

What's your stocking like, and what size tank is it?

Do you typically vacuum your substrate, or have you mostly left it alone until now?

 

[jeffkrol]

How old is the tank?
Looks like a lot of tannins leaching out if the wood.
New wood somewhere?

Mulm and fish might not be exactly related though could be just some shift in water parameters stressing the fish to the point of some pathogen
kicking in, if not outright stress. Or high tds.

Plant on the right us pretty dead now?

Only time I've seen rapid mulm buildup is with bunches of plants or algea dying.
Fortunately never had that happen in a tank w/ fish.
Stuffs sticky too. Any substrate disturbance just has it sticking to plant leaves as it settles. Sort of a never ending cycle.

Sorry just thinking here. No answers