Have been having problems getting my water crystal clear. No matter what it is always hazy / mirky looking.

I have two TetraTec external filters rated at 1200 Litres/Min.
Also internal Juwel filter rated at 1000 Litres/Min and added Hagen powerhead with sponge to filter fine particles out.

Have done 50% water changes 3 times with 2 week intervals between each. Tank is 260 Litres.

Have one 8" Oscar and two 6" Barbs.

Whats going on with the water.

Nitrate,Amonia, etc is fine.

Could it be a lighting problem rather than water.

Might add that I used to have sand as a substrate and have removed from the tank. The tank has been empty of everything bar water:laugh: for last two weeks and still cloudy.

What exactly are your ammonia and nitrite readings? Have you been using a water conditioner when doing water changes? Have you washed your filtration media out at all on the tap water? Did you suddenly take all the substrate out all at once? How much have you been feeding your Oscars? Is your tank cycled?

Redone tank yesterday with gravel, etc.

Cleaned out filters and replaced some elements. Tank looking 100 times better. Still little mirky but settling down.

I think it was down to the use and removal of the sand I had in tank. Not wise to do on a running setup. Have however switched to 3mm river gravel.

Noticed that filters were full of sand. As my Harry likes to scoop up the sand in his mouhth and spray it everywere. This is then getting into all the filters.

Anyway added a pick in Aquarium Gallery of the new setup. Its looking good and Harry seems to like it.

You said you removed the sand and replaced it with
river gravel. Why is that? I ask because as I have said in other posts I'm planning on getting a 150gal and don't know which substate would be the best. I currently have the river gravel myself.

Personally i would always use gravel for a substrate with Oscars. I just feel that when they start digging around in the substrate that sand is not a good thihg to have passing through the delicate gill plates

Help! I have basically always had perfect ammonia, nitrite
and a good range for nitrate. The PH is perfect from the tap but falls. I currently have a 30 gal with alot of fish and have a whisper 5 running and a new cascade 1500 canister which I'm running mainly to get a biological ready & going for my when my 150 arrives. I also have a undergravel filter too.

Anyways, I have been doing water changes every 2-3 days
which is fine while I awaited my new tank. But, all of a sudden my ammonia is climbing ? I have now been doing 75% water changes for the past few days, everyday and right after the water change the ammonia is still higher then it should be. Does changing the carbon at all
help with this ? Why is this happening & what can I do?
Or, is it simply there is too much for the tank to handle?
Is maybe to much filtration/power in a tank not a good thing? As, I said I have a underground, a whisper 5 and a
cascade 1500 on this 30 gal (the cascade is really powerful).

Sorry, to over power you with questions but once again I'm being thrown a curve ball and don't know what to do. I don't want to panic too much and then do something to make
matters worse.

Thanks in advance for any help!