So, this goes back at least a month ago when I tried out sand for my 2 split Betta tanks. I hated it, entire tank was white but very cloudy and smelly like the beach (COULD NOT SEE THE BACK WALL). I did not realize it, but had bought a mystery snail because I am having no luck with Nerite snails doing what I want them to do (they don't move around much and then I cannot find them, and they die or I have no idea what), and mystery snails are gross pigs although I love their activity, so since then I have started a whole new tank for just the mystery snails (4, one for each side of Betta tanks) so they would not gunk up the betta tanks. So, nothing but Bettas in the tanks now and the snail tank is great, they are loving it. Anywho, I changed the sand out, did an entire tank breakdown, cleaned everything in dirty tank water, put a new filter in each tank because of the disgusting snail gunk on it, but kept media from the old ones, used the old gravel and put it all together, filled them, they looked great for 5 days. Started getting cloudy again, and I have no idea why. I assume a bacterial bloom because of the new cartridges I put in but it is not clearing. I just did probably a 45% water change so we will see, but also went to amazon, ordered a stronger pump for these tanks, with prefilters so I do not blow around the fish, and for each side of the tank I ordered a foam filter with a single air-pump with 4 outlets on it. So, waiting on that, but never had any problem with the filter on these tanks, so not sure what it is. Before putting it back together, I checked the impeller, and the flow is pretty strong, but the back channel where these built in filters go seems stagnant, not sure why, but water is flowing out, pretty strongly. I just checked parameters before water change and they were all fine. The nitrates are hard to tell if 0 or in between 0 and the next color. It seems middle. These tanks have been up and running for months until I put sand in them and I messed with them. They were never cloudy before in same tanks until I put sand and mystery snails in them. The cartridges were changed right before the mystery snails were removed, so may have to replace them again even though I have rinsed them numerous times in tank water. At one point, with the snails in there, I added another filter to each tank and it did nothing. So, breakdown, good parameters, just betta fish, split tank, 5.5 gallons (I know some of you do not agree with this, but I do not have room for bigger tanks), all fish seem fine, eating, did 45% water change today, still cloudy water. Any ideas? I hate to take everything out again and start all over but when the new pump and little sponge filters come will have to move it to put these in, so will have to do most likely a 75% water removal so I can lift it.