Hello,
I have a 5 gallon fish tank that I set up on may 15, on may 18 I put in 3 glo fish and a live plant. It was fine for a week or so then the water started to get really cloudy. I realized I had been really overfeeding the fish so I cut back to one feeding every other day and the water got almost clear, then it clouded up suddenly and I realized the roots of the plant were dissolving and though it was still green, the plant was clearly dying so I removed it completely. Following the advice of my local pet store I did a 30% water change and it was just a cloudy the next day as it had been. The cloudiness is white and smoky looking. I have tried nutrafin cycle, I treated the tank once then again the next day and it didn't seem to change anything. I had the water tested at the pet store and they said the water is completely fine. The tank is open top so water evaporates out quickly so I add about 10 ounces of tap water every other day. I had been using tap water conditioner when I added the tap water but the pet store guy said to stop using it because it might be making it worse. So now it has been over a week with nothing added to the tank, only little bits of untreated tap water. I was doing weekly 10% water changes and using a vacuum to clean the gravel but now I'm even afraid to do any more water changes, I thought just leaving it completely alone would help but it hasn't... I'm at a loss about what to do, the fish seem fine but I can barely see them unless they are near the walls... please let me know if anyone has any ideas about what I should do to fix my tank water

My tank used to fog up until I got a couple sucker fishes they clean the tank for you ,and get water filters to put in the tank so it cleans helps clean the tank and makes it easier for fish to breathe

What kind of filtration system do you have in the tank?

EHEIM Classic External Canister 40 gal tank

It's a tank called a fluval chi... I'm using the pump filter that came with it, it uses a sponge and a carbon filter, I've changed the carbon one last week but I've only been rinsing the sponge one in dirty tank water

My first thought is that you are over feeding them but you say you are being careful about that. So what comes next? Filtration. I'm not real familiar with the Fluval set up but if it's like many other all in one tanks, the filter is probably not all that good.

It may help if you get a tank vacuum and clean the gravel as there may be food remains in it. A small catfish may help to keep the bottom clean if this is what your problem is.