I used to change my water by one bucketful each week. If the bucket is left standing overnight the chlorine comes off it and it also comes up to temperature. Take a bucket full out with a siphon and then replace it with the standing bucketfull. Worked for me for years. Cloudiness caused by over feeding, my grand daughter does the same in spite of being told not to. Just put enough food in for them to eat in a couple of minutes and just once a day. Realise may be trying to teach my granny to suck eggs but just in case.
The problem with modern water supplies, is the water companies are increasingly using Chloramine instead of the more costly Chlorine to make the water safe, and that does not disappear naturally, it can only be removed using a man-made agent.
Ive never had a problem with cloudiness in all my years of owning a tank, so I dunno if as jase says, its more down to the quality of the food; I don't overfeed by choice, but im sure I must do sometimes. I do however insist on using known brands like Tetra, im currently using King British and Aqua One Spirulina and PetsAtHome plec algae pellets as the staple food supply (with variation in fresh vegetables etc), and never had a problem.
My mum on the other hand uses the cheapo food you buy in the likes of Home Bargains, and she does sometimes have issues with cloudyness. The filter she is using is more than big enough for the tank, so it could well be the food.
I have a Rio 400 with is around 450 litres, and a Rena XP4 filtration system, suitible for around 600 litres iirc, but it can't be tank size as I used to have a 30 litre tank, with 3 goldies in (babies) and that never got cloudy either. Actually, at present, im running an unfiltered 25 litre tank, with Baby
swordtails in, and that too doesnt get cloudy, do its nout to do with filtration or size.
As people have said, when getting plants, always wash them first with some water out of the tank, as snail eggs tend to enter the tank via plants, and if they have come out of bad water, they could potentially infest your tank with unwanted/harmful bacteria. The same applies to the filters, when washing them, just use water out of the tank, and dont squeeze etc, too hard, as you don't want to damage the biological filtration element, which is the most important element in a properly cycled tank.