i am currently running 2 rena xp3's on a 225 gallon tank, the fish are a 5 " tiger shovelnose, 10" needlenose gar, 10" lime shovelnose, 4 inch pictus cat, 6 inch silver tip shark/cat, and a 12 inch pleco. I notice lately the bed of the tank is extremely dirty, perhaps Ineed a third filter? Any suggestions...

could you tell how often you vacuuam you tank. i do my 46 gal once a week and i have a xp3 and a ac300 hob filters and my bottom of tank is doing fine

That could be a sign of over-feeding.

i vacuum once a week and drain 20-30 gallons water cycle weekly. I add aquarium salt to the tank and all my other tanks are fine, maybe the types of fish are bigger and messier. I also noticed today that one the pictus and the cat-shark look to have either ich, or velvet. All the rest are fine. I just recently tried a new supplier for feeders so I am thinking something screwy was up with this batch. Treating a tank this size... anyone with suggestions? All of my other tanks have never had a problem so this is new to me. I have read to raise the tanks temperature and ad salt as well as many medications that can be used, i already have the tank brackish and the temp has been raised to 84.6. so perhaps the next step is to medicate?... I just dont want to harm the other fish. Someone help!!!

For the dirty problem, I'm pretty sure your tank needs a lot more filtration. the rena xp3 has only about 350gph each, so you are at about 3x filtration. I would increase the filtration by double or triple. My 135 gallon tank has a rena xp3 and two emperor 400s, getting about 1100gph and I find that okay.

Adding 2-4 large HOB filters should fix up your dirty water problem. Or if you have a lot of extra cash, a large canister filter or two. A powerhead with a quickfilter is not bad too for taking out dirty particles.