please help

hi all
im new to the salt water hobby and i think iv done well so far
but lately iv developed a bad alge problem.
all my rocks shells sand and corals are covered in a brown sludge.
some of the corals even have stingy brown goop comin off them.
i use only ro water which iv tested before putting in the tank to check its of good quality and all seams fine. the problem is my chemicals readings are fine other than phosphates which read off the scale.
i have no idea where they are coming from.
any ideas would be great.
thanks guys.

 

a pic would be great. It sounds like diatoms or cyno. How old is the tank? New tanks almost always go through an algae phase.

 

Test the RO/DI water that you're using for phosphates before putting it in your tank. You may need to change out some filters. If that's not it, the only way you can get the phospates out is slowly by water changes and using phosban/phosguard media to absorb and trap the phosphates. You may be overfeeding or feeding too much frozen food that's high in phosphates as well, so check that out and maybe cut back on feeding only as much as needed.

 

Be sure to check out the 'sticky' threads on the algae board as well. Diatom blooms have been well covered.

 

its about 5 months old now and so far this is the first prblem iv had.

 

That really is some ugly nasty stuff you have choking out your zoas.
What's your action plan?

 

Do you have a clean up crew? (snails, crabs, so forth)

 

i do have 2 hermit crabs but thats it at the moment.
iv just bought an aqua clear which claims to remove phosphates.
if that fails i will try fluval phos-ban.
any one know if either of these works?
with what i have read the phosphates are causing the alge but i cant figure out where the phosphates are coming from.
product water from my ro filter is reading zero on all tests.

 

How big is the tank? 2 hermit crabs won't do much of anything unless the tank is a very small nano.

 

is 120 litre about 2 feet wide 1 foot at its deepest (bow front) and 1.5 foot tall.
originaly i didnt buy the hermits as a clean up crew. they were for show.