1 one week after setting up my first pool I got my first case of algae bloom. Once I got the algae killed I was having problems getting my factory pump Model 635(1500GPM) to filter out the algae. Rotating with 3 filters every 8 hours and spraying them clean I was not making much headway on my new pond.
Replacing a filter I noticed that wasn't sealing completely around the filter housing lower outer tube(Poor design). A trip to Home Depot landed for less that 3$ a rubber drain/tub washer. Inside diameter is 1 7/8"(important), outside diameter 3" and thickness 1/8". Slide the washer over the tube. If you slide the washer to were it is flush with the top of the tube you can use a dry filter to push it the rest of the way down until it hits the top outlet port. If the washer gets pushed further down and does not stay parallel to the bottom of the filter you will loose seal effectiveness. This trick works with both "A" and "B" type filters because they have the same inside diameter. The filter is about 1/8" shorter that the filter housing space allocated for the filter so the 1/8" thickness of the washer will not cause compression of the filter. You could put a washer on the top but I don't see much need in it since all the caps have a plastic ring that fits in the groove on the top of the filter to stop blow by.
This should help with filtration but not solve the low sq. ft. of filter capacity of the Intex filters.
I just order a Unicel C-5345 from PoolSupplyWorld for $21.37 + SH it has 45 sq ft and I plan on using it for the "B" filter replacement. It dimensions are 5-5/16"W 10-1/8"H and 2- 1/8" Hole ID. I will use the washer trick on top and bottom and carefully install cover since it is 1/8" taller that original. The Intex Type "B" filter is 5-3/4"W 10"H 1-7/8" Hole ID and 15 sq. ft.
I will let you know how it turns out.