Diatoms bloom month 4

[benboarder90]

Hello everyone, hope your tanks are doing well

So I’m still having a diatom bloom at month 4. I’m sure I know the answer/ root cause. Just want to make sure I’m not over looking something or missing the obvious. I feel I have a bad membrane or 2 and it’s letting silica through.

My tank is a 75 gallon
Start date April 17th 2026
Brand new BRS 75 GPD RODI
I have a full back up set of filters.

I feel I have a good clean up crew
Urchin
20 + hermits blue and red leg
15ish assta snails
5-10 margarita snails
6 nasaria snails
1 tiger conch
3 emerald crabs

60 lbs live rock (35 lbs was dry rock)
60 lbs live sand

2 clowns
2 cromis
1 blue damsel
1 valentine puffer small to medium
1 6 line wrass

Ammonia 0
Nitrite 0
Nitrate 4
Phosphate 0.10
Cal 440
Alk 8
Mag 1300
Ph 7.9

I do a 10 gallon water change bye weekly
I have a bubble magus curve 5 protine skimmer
10 gallon sump

Thank you for any input or if it is the silica

 

[Tahoe61]

Have you added any new equipment?
If possible an image might help. Are you sure it's diatoms?

 

[benboarder90]

 

[EnterName]

Diatoms are usually visible on the substrate first, rather than the rocks. To me it looks like you just have some green coralline starting to grow on those rocks and the tank walls.

The image above shows actual diatoms on newly added dry substrate that released silicates in my 6+ year old system (see also page 5, post #91 of my microscopy thread). The coloration is often quite dark and like "dust" on the substrate. In severe cases tiny "hairs" can grow which are clusters of diatoms connected to each other which you can see in the linked post as well. While bubbles are more often associated with dinoflagellates, in "severe" cases diatoms can form bubbles as they are photosynthetic as well.

 

[Privateye]

I concur. This doesn't look like diatoms to me.

It does look like something a Dobie sponge could handle though. The stuff on the back wall does look like it could be green coralline algae, but the stuff on the pipe does not. Perhaps the back wall just has a buildup of the same alga on the pipe. I'd clean that heater before it gets too bad.