Have you tested your Phosphates? You want .03 or less. Yours may be as high as
2.0 or more.

Siphon out all that you can see, using airline tubing. You'll lose a little
sand in the process. If you are really attached to your sand, the stuff
siphoned out can be boiled and put outside in the sun for a few days before
adding it back to your tank.

Do you have any creatures to stir the sand, such as hermit crabs, fighting or
queen conch, cucumbers, etc... They can help keep things cleaned up.

How old is your lighting? If the bulbs are old, you might be dealing with a
spectrum shift, which fuels unwanted algae growth.

Marc


Mark wrote:

I have a 125 gallon reef tank with a deep sand bed. That's 4-5" of
Aragamax sand. I find that I am having horrendous problems with red
algae covering everything. I did a 50% water change last week and
already everything's covered again. I can practically set my watch by
it.

All fish are very healthy (growing noticeably) and the corals (pretty
much all soft) are as healthy as they can be considering they
regularly get covered over by a sheet of red algae. The algae that
forms on the sand normally has a lot of gas bubbles that form under
them and within a day lifts a sheet of it up to the top of the water
and it gets pulled to my overflow.

Everytime I test my water parameters, they look very good -- no
ammonia, undetectable nitrites and nitrates. I find the Ca and
Alkalinity to be rather strange though. The Alkalinity regularly is
in the vicinity of 12meq/L while Ca is something like the high 300's.
As I'd understood it that was not supposed to be possible. I also
confess that I have not been super-good about adding Ca and buffer
solutions on any kind of a regular basis.

I've done some looking and the answers I see to the problem of red
algae in a deep sand bed tank are either a) you need more water flow
or b) you need to recharge the fauna in the sand. I had a slightly
more powerful pump in the tank when it was first setup, but I found
that it started to blow the sand around and it looked like a hurricane
in there. So I backed the circulating pump off to a slightly lower
flow model and it looks good to me. I saw no dead spots. Recently,
in an effort to see if even high flow would help, I put a reasonably
high powered powerhead in there which really moves the water now. No
effect on the algae problem or its rapid reformation whatsoever.

I've had this problem for many months and had recharged the sand
critters within the last 6 months. I take it that since I have gas
bubbles forming on my sand under the red algae, and that feeding
doesn't seem to be polluting my tank, that says that the deep sand bed
is "working" on some manner.

I feed 1-2 times per day and try not to overfeed, although I've heard
that that's not as likely to be a problem with a DSB tank.

I could throw more $$ at getting an influx of sand critters yet again,
but I have no clue that it's going to help as it didn't really before.
I'm finding that the enjoyment of having a reef is rapidly getting
replaced with the disgust of remove red algae from everything but the
fish every couple of days. I've heard of the red algae removers, but
as I understand it, those kill other things and I don't particularly
want that.

Any help would be greatly appreciated. And if anyone has a need for
some red algae, I can let some go real cheap :-).

Thanks

Mark

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