Currently battling some brown algae (diatoms?) and I need some feedback on how to beat it.
I have no idea why, but I seem to avoid the BBA, cladophora, and hair type algaes in exchange for the diatoms and GDA, which have been surprisingly challenging for me to deal with.
You can see what I'm talking about here...
this stuff is related to the fuzzy diatoms I've been dealing with, but I'm not sure. As you can see, it's affecting some of my plants pretty seriously. My staurogyne and HC are essentially dead because of it - they'll grow a few new leaves, but at that point everything else subsequently starts getting covered by brown gunk. When I trim the affected stuff off, the process just starts from scratch. One step forward, two steps back.
My C. willisii and a. nana have also been hit by it pretty hard, and while it's not killing them like my stauro and HC, they're not making any forward progress at the moment. My eichhornia and blyxa are growing great, and my r. nanjenshan seems unaffected by it too.
Here's my tank specs, in case anyone feels moved to help me troubleshoot...
- 40G breeder (36x18x16), current set-up running 6+ months
- 2x39 watts T5 retro-fit with AHS-equivalent, top end reflectors - approximately 25 inches above the substrate, 8 hour photoperiod (had to keep moving these higher to beat some GDA)
- CO2 with in-line Rex reactor - 3+ bps (bright yellow drop-checker). 1/2 tsp N, 1/2 tsp K, 1/8 tsp P three times/week
- 1/4 tsp Mg, 1/4 tsp Ca two times per week
- 10+ ml CSM+B, 2x recommended Excel three times/week
- weekly H2O change - 75+%
- moderate (IMO) fishloadL: 13 cardinals, 7 c. habrosus, 5 dicrossus, 1 nannoptopoma
Any ideas on what to do to fight this brown crap? Am I right in thinking of it as diatoms? If so, I've seen people deal with it by both cutting and adding light - any suggestions there?
As an aside, "brown algae" is a term that seems to apply to any number of different things, so it's been hard for me to find good, solid information on this exact type...
As far as next steps, I'm leaning toward trying some window screen over the lights next, to see if maybe I'm still too photo-excessive, but I'm open to almost anything.