Is my new reef tank algae problem caused by overfeeding?

We're new to all of this, having recently setup a 123L Fluval Flex reef tank in my wife's office. It finished cycling, and we added our first livestock a couple of weeks ago - a couple of clowns, a cleaner shrimp and a half dozen snails to munch on a little bit of brown algae that was forming on the rocks. The tank chemistry seems really good - no ammonia or nitrites, nitrates are only about 2 or 3, ph is 8.2, salinity is 34. We're feeding half a cube of defrosted tmc marine cuisine nano once a day, which they seems to polish off in a couple of minutes (although we are leaving the pump on, so it does get spread around).

So, all was good until a week or so ago when we started to get some green fuzz on the rocks, and then a good coating of green on the inside of the glass. The water's actually clear though. So, quick scrub, and it's gone, but back again 2 or 3 days later. The snails for a good job each night of munching away, but can't keep up.

We've just added a few small soft corals, so I can't just turn the lights off, but I've turned them so they're only on white 6 hours a day and blue for about 10 (including the 6).

Having read "it's light and food", I wonder if we're over feeding - even at this small amount. The floss in the filters is going light brown after only a couple of days and does smell a little, well, fishy.

Any thoughts on what to try? Anything else chemistry-wise to check for? As I said, the water's staying clear at the moment, and it's mostly on the glass and the plastic. It wipes off with a scrubber pretty easily.

Thanks in advance

pete S

picture of the algae?

Hi Colin. Well, I knew that was going to be the obvious question, but I'd just cleaned it, so wasn't much too look at. So, after cleaning it about a day and a half ago, here's a couple of shots which give you an idea.



You can see the green whatever it is growing on the aquascape. The snails have a good munch on it at night and it gets more during the day.



You can just see the green starting to form on the inside of the glass - this is pretty widespread after a couple of days.

I fiddled with the lights this morning - it's the Fluval Marine 3.0, so i've turned red down to 20% and white down to 50 or so.

Chemistry still all looks fine - nitrates are 2 or 3, ammonia and nitrites are 0, ph is 8.2, alkalinity is 12, salinity is 34-35.

We've got 4 snails at the moment - did have 5, but one coped it for some reason. Probably need some more, but want to try and understand what's causing the algae to head it off at source if possible.

The snails are doing their best, but the glass is greening up again.



Any ideas of the likely cause or remedy?

Too much light, too little light, too much food, too little food. Its unbalanced, try feeding every other day or playing with the time your lights are on.

I can certainly drop the lights a little more - both time and remove a bit more white and red to see how that helps. If we're overfeeding, will it show up in nutrients/nitrates? We're only doing half a cube per day, but I'm conscious that the filters are browning after only a couple of days - which kinda suggest nutrients to me, but the nitrates are only 2 or so. We're so new to it all of course so it's all guessing.