slow - zero coral growth

[saltyrockbox]

I have had my tank for a year now and have a variety of corals softies, LPS, and one sps frag. All survive but they have not really grown at all, some tiny growth but really very very little in all. SOmtimes one will grow a bit and then stop. Even hardy corals like GSP seem to be slowly looking less healthy. (over the months)

My water chemistry seems great, but maybe not the most stable, I have moved from one big water change a month to weekly 10% changes, I have more crabs and now have zero algae in the display but I do have sheets of nasty algae in the overflow. I have a new ballest and more light power (4 over driven T5s covering every inch of the top).

It could be...a low flow problem, an unmeasurable nutrient problem, a toxin released buy the overflow algae (slimy algae) or the lack of perfect stability in water chemistry.

So I might have answered my own question but I'm posting because maybe someone knows something I might never think of...

Any Ideas??

[Der_Iron_Chef]

I think it's always a shot in the dark, when you're hazarding a guess as to why two different tanks with seemingly similar statistics, experience such different growth rates.

My tank has never been really stable, for example. I don't have an auto top-off, and my water changes were sporadically regular. I dosed for Ca & dKH, except when I didn't...etc, etc. But I experienced some pretty crazy growth in some corals (some of those SPS). Others, like my purple mushrooms, which by all accounts should be spreading like wildfire, split at a snail's pace.

Having said that....what is your bioload like? Livestock? Do you test regularly?

[saltyrockbox]

75g tank bioload 3 small clowns, small 6 line, small foxfaced rabbit fish, I feed a 1/2 cube of frozen whatever I have or a pinch of flake every day, lots of zebra and blue hermits one starfish and one coralbanded shrimp,
I tested nutrients for a long time and for about 3-4 months was getting zero, I have been dosing Ca & dKH by hand after testing a couple times a week I have auto top off and with the new lights and fans go through A LOT of fresh RO water. My RO system is crapy nano systme i got a while back I have not tested its performance, maybe I should do that.

[saltyrockbox]

I guess there are a lot of little things I can work on. I have a little red mushroom that finally split I thought it was going to die but also have some big furry mushroom that have never ever grown, lots of colt frags that grew for a bit then never grew again...I got a hammer that grew a lot for 3 weeks then stopped.
DO you think the slime alage can inhibit growth?
DO you think I need to add any supplements? a lot of people dont and have good results with regular water changes as the only "additive" I use IO salt

[fishoholic]

I found my corals grew a lot more when I switched from T5's to MH.