Cloudy water, established tank.

[Oldroamer]

My tank has been set up for about five or six years, it has sand substrate. For the past several months I have been experiencing cloudy water. I have stirred the substrate and “hovered” it, carried out numerous water changes ranging from usual five litre to fifty percent.
I have cleaned the filters and have one full of sponge, the other has half sponge and half floss. I have tested water parameters and all is well.
The fish; 3 corys, 1 adult platy and one baby born in the tank a couple of months ago and one honey gourami seem fine and unaffected by the cloudiness.
I have an unknown plant in the tank which I have thinned out today, I do this regularly but it soon grows until it takes up about 50% of the swimming space.
My only other option is perhaps a complete strip down and rebuild but would like to avoid this if possible.
Any ideas?

 

[MattW]

Not too sure on this one sorry. Your corys will dig and stir up the sand, but you mentioned you have cleaned it thoroughly. The decor could be the cause. Sometimes decor has been known to leach into the water and turn it cloudy. Is that real wood or resin like the barrels?

The plant looks like Hygrophila polysperma also

 

[Innesfan]

When you say you cleaned the filters, did you rinse the filter medium in aquarium water? Barring something leaching, as @MattW suggested, cloudiness is most often a bacterial bloom and sometimes an indication that the tank is recycling. So you want to preserve the beneficial bacteria colony in the tank and especially the filter. Any cleaning/rinsing should be done in aquarium water to that end. Over-zealous cleaning is counter-productive and cleaning in tap water will aggravate the problem. I recommend patience, regular water changes and monitor the water parameters closely.

 

[Oldroamer]

The log is resin, I did have a small piece of bog wood but that become very dark looking around the same time as the cloudiness started so I removed it. I always clean my filter sponges in water removed during my water changes.
As the cloudiness seems to annoy me more than the fish I will sit tight and hope it runs its’ natural course.
Many thanks for your replies.