I read through this (short) thread when I was debating whether to go for Clinobrite or not, about a year back. I did go for it in the end, so I now have some experience of both types - about 5+ years' experience with ordinary silica sand and about 1 year with Clinobrite. The reason I re-packed my filter in the first place was because I had emptied it to check for broken collector arms (laterals) at the bottom of the filter anyway.
Sand filters are nice & simple when compared to fancier types like cartridge (membrane) filters or the older diatomaceous earth (DE) filters. The downside is that they don’t filter quite as well - only down to about 20 micron particle size, whereas a good cartridge filter can get down to below 5 microns easily. Silica sand is also completely inert - it filters by physical action only, not chemical. Contrary to what some manufacturers would have us believe, I don't think it ever really "wears out". This is borne out by some folks operating filters with the same silica sand for 10+ years. So the positives are simplicity and long life, the downside (to some) is that your pool water is just “adequately clean”.
Because of it’s non-smooth grain structure, Zeolite (Clinobrite) is claimed to be able to filter out smaller particles - the claim is about 2-3 microns. Unlike silica sand, it also has both a physical and a chemical action, ie it also cleanses the water chemically by cationic exchange. Without doing some fancy measurements, I can’t say if the 2-3 micron claim is accurate, but whether because of that or the chemical action, I *can* say that my pool water is perceptibly cleaner and much sparklier with Clinobrite than it was with silica. That’s the upside.
That same chemical action has a downside, too - it means that the Clinobrite goes “bad” after a while and needs to be regenerated with salt solution. In my case (residential pool, 45 000 litres, salt-chlorinated) that took a about a year to happen. Nothing really bad happened (ie the filter still worked OK), just that the water was somewhat cloudy and not nearly as clean as before. Regenerating is no big deal - take the lid off the filter, fill it with strong salt solution, let it soak it overnight, purge the next morning and voila - my pool was back to stunning within 24 hours. Interesting that the water that came off the filter the morning after was pretty yucky. Pool salt is about R50/25kg and if you have a salt chlorinator, you’ll have lots of it around anyway. (Something interesting is that this "salt regeneration" is similar to that which happens in a dishwashing machine - the cationic resin in the water-softener needs to be regenerated with salt regularly).
As for costs : at the time I shopped (Nov 2012), silica sand was about R75/40kg and Clinobrite was R150/40kg. Yes, Clinobrite is double the price but at about 3-4 bags for the average pool filter (< R600) it's not a huge outlay, at least once off. That said, I don’t know how long the Cinobrite will last. The “1-year” recommendation referred to earlier in the thread is for pools with “heavy bather load” only. Mine sure bounced back well after the first regeneration at 1 year.
Bottom line, in my opinion : much cleaner/nicer pool water, but with slightly higher initial cost and slightly higher maintenance requirement - I reckon 6 or 9 months between salt treatments is probably about right for the average residential pool. Also bargain on perhaps 3 - 5 years before it needs to be changed completely - I dunno ?
Is Clinobrite worth it for me ? Absolutely - my pool’s a pleasure with it.
Hope this helps someone else!
