My frst post! Green water problem!


New member
Hello ReefCentral! After reading posts on this forum, I`ve decided to join. I have a major problem!
I have had green/yellowish water in my 40 gallon breeder tank, it`s a coral prop tank. I use a skimmer, carbon, polywool, power heads, 20lbs of live sand and 20lbs of live rock. I have a 400W MH 6500k and no direct sunlight. 12H per day. Many people on other amateur forums told me that it was my light. It`s not true, my friends uses at least 7W/gallon 6500K MH lights and they don`t get green water. By the way I hang my light 18 inches from my tank. Some forums told me to use a micron filter, I already now that it`s gonna get rid of my suspended algae problem but I don`t want to just cover up the problem, I want to get to the root of it and a micron filter is like 200$ in Canada! NH3/NH4 is always at 0 and trates+trites are a95% of the time at 0, I use chaetos. I use RO water, I add chlorine and heave metal neutralizer and my salt is red sea the one with no phosphates and extra calcium. If I am missing some information please tell me! I`ve done a 99% water change after this problem persisted for a month! People told me: just to water changes it will go away, it didn`t work... After the 99% water change, it didn`t take more than 3 days before I suspected the water was getting green cloudy again... So now I`m erradicating everything with bleach (don`t worry I took out all the live stuff exept for the sand). And my live rocks are in quarantine, should I freshwater clean them too? Please ReefCentral, help me! I am about to leave this exiting one of a kind hobby if this persists! Thank you in advance!
Last edited:

Bri Guy

New member

Check out this thread, try it.

Then when you turn your 400w over a 40g back on try 6 or 8 hrs a day. Thats what most people on RC run theirs for.

Then find where the excess nutrients are coming from.

btw, don't use FW on the rocks, it will just kill more stuff and cause a real algae bloom.

oh ya and...
<img src="/images/welcome.gif" width="500" height="62"><br><b><i><big><big>To Reef Central</b></i></big></big>

edit, your going to find in this hobby what works for some does not work for others, so just because your friend is doing something, doesn't mean it will work for you.

good luck!


New member
my buddy had the same problem, a good skimmer to rid of the nutrients and a uv will solve your issues at least it fixed my friends.