help with cloudy and dark colored water

"NetMax" wrote in message
...
"wicked1" wrote in message
...
I have a 150 gallon freshwater tank. I have 1 eheim 2028 canister
filter,1
eheim 2029 wet/dry filter,and 2 Penguin 400 filters. I have it heavily
stocked and the water readings are always excellent. No ammonia or
nitrites.
The water just gets dingy looking kind of a brown color and hazy.I
usually
do a 40 gallon every 2 weeks water change which makes it crystal clear.
Would carbon fix this problem? I really dont want to go the diatom
route as
that gets real expensive. Thanks for the help.

-Any driftwood or plants in the tank?
driftwood thats been there for over a year and it was bought and washed all
plastic plants

-What is your gravel vacuuming routine, and how bad is it when it's done?
I vacuum when I do water changes and the water that comes out is black

-Any area you cannot vacuum or are very deep?
No

-What are your NO3 levels and rate of accumulation? (measure your NO3 a
few times just before water changes).
Nitrates are in the middle of the chart before water changes.

- Specify 'heavily stocked' in terms of number, size and approximate
amount of food thrown in.
6 Oscars,2 Tinfoil Barbs,2 Hap rhodesi,5 Parrot fish,2 plecos,1 synodontis
decorus,5 4 line cats,1 ropefish,2 albino channel cats. They get fed between
1/4 and 1/2 cup of food a day. They are all large fish.

- pH readings before and after water change?
ph before 7 ph after 8

-Describe your filter state and service interval.
Filters are maintained very often

I added some algaefix and it made the water alot clearer. I am using 2WPG of
light.I ordered a 18W UV sterilizer too. This tank has been like this for
about a year just hadnt tried fixing it yet. My 4 other tanks (all large
cichlids) look crystal clear. I am beggining to think its algae blooms.I am
adding carbon today too.I have never used it except to clear out
medications.
Thanks for any help.