Diatom/brown algae explosion. Any ideas?


Within the last 14 days, I have had a diatom/brown algae explosion across most of my DSB. I initially thought it was b/c one of my UV bulbs burned out, but I replaced it nearly 1 week ago. I have been testing my water daily since the onset and it always remains the same: Amonia 0, Nitrite 0, nitrate less than 20, sal 1.022, phosphates 0, .....20% water change during initial onset (RO/DI water). Top off are always with RO/DI. RO membrane has been used for approx 1000g of RO water. T-5's on for 9.5 hrs (actitnic with blue). The ony thing that has changed since the onset was the temp. It crept from 75.5+/- to 78.3+/- and has since stabilized to around 76.3, for the past 2 days (tmp drops less than .5 degree during the night). I am at a complete loss. Any ideas?


Active Member
Assuming your tank has been set up a while, the problem is probably silicates. Source water & substrate leaching are usual causes. Easy to test for, I like SeaChem's silicate test, and very easy to remove with almost any phosphate remover. BTW; the tiny temp change you mention won't ever hurt anything and UV won't do much with diatoms.