Thanks both ,but will this floating dirt effect the fish in any way ,and do you get this floating dirt with sand?
it shouldn't. after all, its bin in the tank all the time, just you can see it when its stirred up.
the filter should catch most of it. but some will fall back to the substrate.
I had the same problem as Tizer (large bore syphon 2 inches, i think.). so bought a smaller one (1 and 1/4 inch) just for gravel cleaning. keeping the bigger one for changes only.
funny thing here. the smaller unit actually cleans better, and deeper than the larger bore does.
though the amount of water moved is bigger in the larger unit. but the pressure (or suction pressure) of the smaller unit is higher. so it will pick bigger bits up, and get deeper down.
counter intuitive, perhaps. but true.
they do make Airpump and battery powered, syphon cleaners.
these, instead of removing the water, from the tank. cycle the water through a mesh bag. this means you can catch many of those "floaters" lol and not worry about how full you container is.
I've found the airpump variety, less than effective (but that's just me)
most of the battery ones are much the same.(many agree here)
however the Eheim unit does work, well. but its pricey @ £30-£40