coraline algea problem

[muzz]

Hello all, I was wondering if anyone can give me an idea as to what is happening with my tank and how to correct it.

First off, my tank is a 125g display, with a 75g sump. I am running an octopus recirculating skimmer, which is rated for a larger sytem than I have now, so I am overskimming. I also run carbon, and phos lock in 2 seperate phosphate reactors. I use kalkwasser for all top off, using an auto top off. water changes of 20 gallons are done every two weeks, and everything has been stable for 6 months plus now.

Calcium: 430 to 450 ppm, using salifert kit.
Ph: 8.0 to 8.1 using salifert kit.
Alk.: 9.6 to 10.2 dkh using salifert kit.
Temp: 79 degrees
salt: reef crystals, .1025
Ro water used for all mixing, top off(with kalk).
lighting, 3- 150watt metal halide, 10k bulbs, 4 months old. 8 39w t-5's for actinic suplementation. lunar lights, with a 400w pendant over the sump running a reverse photoperiod as the main display to keep Ph from swinging to much. I also have a frag rack under the halide penadant in the sump.
Livestock is sps corals mostly, also, lps corals, one mushroom rock, 2 bta(was one then split, both are about 6 inches right now). and about 8 fish.

So now to my question, my coraline algea is turning grey/white, like it is dying off. I do not know why, and it has happened to me once before, when i was not running kalk, and the calcium got low. after adding liquid calcium, it all turned nice deep purple again. Can you tell me why this is happening? what could cause it? and how to fix it? Everything seems to be very happy right now, I am just afraid that this could be a sign of something bad, and I want to find out what is going on with my tank. I have added kent essential elements to the tank, as I know that ovverskimming will cause the water to lost trace minerals and such quicker than normal. Any help would be appreciatted. thank you,

[areze]

well my guess is that coralline algea is still algea, and so I think it still uses the same things like phosphates and nitrates. if your truely getting such awesome water qualities, you may actually be starving the corraline of its nutrients...

thats just my guess though.

[muzz]

I always thought that in order to grow sps corals, that you wanted water to be as close to nutrient free as possible. the sump has green algea in it, and I have to clean the glass of the display tank every 3 or 4 days to clear out the bright green film or algea it gets. I do feed my fish a lot of food, as I like to seem them fat and healthy. since i feed a lot, I wanted to make sure I skimmed as much out of the water as I can, that is why i went with a larger skimmer than was needed. I wonder if I am removing too much, and starving it, I will have to do some research on it, thanks for the reply.

[areze]

if green algea is growing, that doesnt sound like the problem.

[Jrmass]

You haven't had any fish die in your tank that you wouldn't happen to know about could you? I had that very same thing happen in my tank and what ended up happening was I actually had my corkscrew anemone crawl under a rock and wither away and fowled my water bad. Tell tale sign of the issue was I could see the coraline algae about 4-5" from the top all the way to the top had completely turned white and the rest remained purple.

Just a thought.

Jason

[reef / aholic]

Have you checked your PO4? What are you using for water flow within the tank?

When PO4- levels are detectable in your water, you will usually encounter a green hairy algae outbreak of either Derbesia or Bryopsis. Derbesia is like hair having long thin strands that cover everything. Bryopsis is fine featherlike which will also cover everything. Sometimes you may not detect any PO4- in your water, but you still have hair algae growing on the rocks. This happens normally because your tank does not have enough water flow, and detritus (powder-like broken-down waste matter or particles) settles in the holes of the live rock. These detritus pockets contain PO4- that are absorbed by the algae and so you can't detect them in the water. Just make sure you have enough current in your tank to keep the detritus off the rocks.

[muzz]

The test kit for po4(phosphates) shows none, at least not detectable, but I know that it is there, otherwise I owuld not have any green algea.

as for flow, I have the main return pump, which is a pan world pump, roughly 1200gph, but runs mutliple things. I have two closed loops, with two ocean runner 6500 pumps, each is roughly 1700gph, i think, not positive on that though. I have a korallia pump on one side, the korallia 3. there is over 40 times turnover in the tank, on a wave machine. each loop return is split into a Y, which helps to create chaotic flow. there really are no dead spots at all in the tank, except behind the rocks I guess.

My wife left the top off one side of the tanlk the other day, and I am now missing a clownfish, a false perc. . I think it jumped out and got eaten by our cat to be honest. I have searched high and low inside the tank, and havent found her at all. Also, there are no detectable ammonia levels. I think it may be a magnesium problem. I need to do a bit more reading again on the chemistry pages. thanks for all opinions, it is appreciated.
muzz