Zelbrite And Pool Dust


New member
Sep 14, 2010
I have been using Zelbrite in my pool for a year and have had to vacuum it weekly, because of a very fine dust that appears on the bottom. I have had enough of it now, I have been backwashing and cleaning non stop. The pool water is very clear, but this dust which must come from the Zelbrite ( If I leave the pump off, or put it on recirc, it does not appear). I spoke with the manufacturer (I am in Perth Australia) and they told me to backwash. It has had thousands of litres though it over the past 12 months, and still it reappears. I vacuum, then backwash. Next day it is back. Never any of the zelbrite itself (eg the "grains") just a very fine dust. Surely it should have blown everything into the pool by now, or is it breaking down to dust?

Chemically, everything is fine - can't find the pool test results but all was ok. Water is crystal clear.

I am thinking of taking the Zelbrite out and disposing of it, and replacing with sand - or can anybody offer any advice to fix this?

Pool 40,000 Litre Saltwater
2 HP pump (1.4KW)
24" Sand Filter
Zelbrite Media


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
Welcome to TFP Richard.

It sounds like you have done much of the troubleshooting we'd have recommended to narrow the problem. Have you open the tank and examined a handful of the media? Do you know what hardness your water is?

Your pump is fairly large for your filter size, and I wonder about physical agitation in the filter tank grinding the media and producing your powder. I think most 24" filters would be better suited to a 1HP pump or smaller.


TFP Expert
May 20, 2007
South Central NJ
Every 24" sand filter I know of has one and a half inch plumbing inside. There is not enough surface area to disperse the water so that it is properly filtered. A 2 HP pump will try to push more than it can handle. This is generating a substantial pressure in the tank.

Side note: If you really have a 2 HP pump, you're using more energy than you show in your sig and with the filter offering the restrictions, will further increase your consumption due to the increased load you are placing it under.

I would expect that the corrective action needed will be to reduce the motor and impeller size to the 1 HP that JohnT alluded to.



In The Industry
Jul 25, 2009
London and France
Yep, I echo what the other guys are saying, you are not filtering the water, you are jet washing the filter zeolite for that size pool and filter 3/4hp is more than enough, the slower the flow the better the filtration (subject to sensible limits).

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