As some of you will know, I've been battling with red and green slime algae for some months now, mainly in my sand.
I went down to my LFS
the other day, and the guy there asked me how much sand I had in my tank (which is a 35g). When I said "about 2" deep" he said "that's way too much, that's why you're having the problems with the algae because its feeding off the bacteria in all that sand and growing in it. If you get rid of most of the sand, so it just covers the tank bottom, that will cure your algae problem".
Is this true?? My phospates and nitrates are fine, as are all other parameters, so I shouldnt think it's anything to do with the water quality. For lighting, I use 2 x T5 36w whites and 2 x T5 36w actinics, on for 12 hours a day (10 hours for the whites). I feed quite sparingly, and have 3 small fish in my tank. Water circulation is from 2 powerheads and the output from my filter.
I don't have a skimmer.
I use RO
for my bi-monthly 15% waterchanges, which gets the water down to 001-003ppm.
I've also been using Kent polyox (2 courses) which is meant to get rid of the bacteria that the algae feed off, but after 2 tries it hasn't worked in the slightest.
I haven't always had the same algae problem - my tank is now 18 months old, and after about 3 months in I got the usual diatoms and massive green hair algae on my rock, but the cleanup crew (12 dwarf blue/red hermits) sorted that out. Then my current algae problem (which is mainly red/brown/green slime algae all over the sand and stringing from the plants, and also on the glass, which grows very quickly) started after a year.
The main thing I'm concerned about with removing most of the sand, is that I dont have any liverock - I use my external Eheim filter for my filtration. If I remove the sand (which is the bagged live sand) won't I be asking for problems by removing a lot of the "good" bacteria that are constantly converting ammonia into nitrites and nitrates etc.?
Can anyone help me?