The Flow Under gravel Filter is a biological filtration system for fresh or saltwater aquariums. The filter circulates water through the gravel bed and oxygenates it for beneficial bacteria growth. The slots on the filter plate have been designed to draw water evenly over the entire plate from front to back and left to right. The high tube connectors are molded into the filter plates to offer a secure grip onto the one-inch diameter lift tubes to keep the tubes from being knocked out by fish and preventing gravel from falling under the filter plate. pls see the Pipe diameter on item page, it's the size suitable with a filter, and it could using with any kind of filter, or a submersible pump or outer filter.