Sand Filtration vs Glass Filtration

by Christine

I have a 36x20ft pool that I have just resurfaced and 2 consults said my cartridge filter was too small from previous owners. Just getting into taking care procedures of the pool & finding the right pool test kits also. I have read the internet regards to Glass being very efficient and less cleaning. But I don't want a hype from a company ads either. Just because I am a novice I like to get your expert opinion on this type also. I do understand start-up is more expensive, but would like your opinion or advise.

Hi Christine.

A good rule of thumb is 100 sq. ft. of filter surface area per 10,000 gallons of pool water at minimum. Pools over or close to 25k gallons would need at least 400 sq. ft. Cartridge filters rate between sand (the lowest in efficiency, and DE, the highest). Always go with a slightly larger filter.

Now on to the glass. I will assume it's a Zeolite product, or something comparable. You're right that there's much hype and marketing for products. They want their product to be the best in the world because they want to sell you something. The question that needs to be asked is, is it real or hype?

Glass is efficient, similar to sand, but I don't believe all the hype that surrounds it. Glass came out after I stopped my pool route, but have seen a few filters with glass. They seem to do a fairly good job at filtering. One thing that some of the literature mentions is its better capacity to clean, yet less backwashing. If it cleans better then it gets clogged faster which requires more backwashing. I hope that makes sense.

You may hear that Zeolite or glass absorbs ammonia, but so does chlorine. When ammonia combines with chlorine, and it does very quickly, the result is monochloramine. Now the question is does glass/Zeolite remove monochloramines?

Some may say that it reduces combined chlorine which will decrease your chlorine usage. Combined chlorine is the result of not having enough FC to kill organic matter in the pool (sweat, spit, urine, grass clipping, etc..) I cannot see how glass can reduce CC when you need to super-chlorinate to kill the excess organic matter in the pool. This is when marketers and salesmen backtrack and say, "Well, that's what I meant."

Honestly, if you want a system that requires a Multiport valve or backwashing like sand or DE, I'd choose DE. Look at my Q&A page in the sand and DE section. Many questions. Now compare that to the cartridge filter section. Comparatively few. Sand/glass/Zeolite would be my last resort for a filter.

DE filters the best but you need to recharge the grids after backwashing. The grids may rip and you'll get DE back into the pool. Replacing the grids can get expensive. But, taken care of, they'll give you years of pool enjoyment and clear water.


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Pool Sand Or Zeobrite Extreme Sand

by Thomas

I am having a pool installed and the pool builder is installing a hayward with a 24" filter. my question is should I go with sand or I was thinking of using zeobrite extreme. what is the best option. the area where pool is going is very sunny and very little debris from trees. only debris is some pine needles.

Hi Thomas. My honest opinion would be to go with a cartridge filter. They rate between a sand (least effective) and DE (most effective). Cartridge filters don't have laterals or stand pipes that can break or sand to go back through the returns. DE grids can tear and may cost up to $200 to replace. You also need to take into consideration a multiport valve that can stick and spider gaskets that wear out. If you go on my Q&A page and compare the questions I've received from sand/DE filters compared to cartridge filters, well, there's no comparison.

Cartridge filters are not without their drawbacks. You must manually take them out and clean them. Also, your CYA can tend to rise a bit faster due to not needing to backwash, thus, not as much clean water added back into the pool to dilute the CYA. And they need to be changed out every 2000 - 2500 filter hours.

Still, all things being considered, I'd go with cartridge.

Now to address your question, I'd first direct your attention to this answered question:

Sand has been around for decades and is fairly effective at removing debris and bacteria from the water. Here's a line from the above post:

"One thing that some of the literature mentions is its better capacity to clean, yet less backwashing If it cleans better then it gets clogged faster which requires more backwashing."

I really don't believe the hype surrounding the "new and improved" glass/Zeolite/Zeobrite product. They have a product and want to sell it. They'll make it as attractive as possible, explaining all the "benefits". But, as with the statement above, a little common sense can go a long way.

I'll give you another example. I recently did a video that caught the eye of the president of the company. You can find it here:

The bottom comment says this:

"This also breaks up chloramines in water and is why No Mor Problems says you don't need regular maintenance shocking with use."

If you keep your stabilizer and free chlorine levels correct you won't need to shock anyway. Why do I need to add another (purchase his) chemical to the water to tell me I don't need to do something that I'm already not doing? You see, it's the same kind of fancy writing to entice you to do or buy something. He has all kinds of EPA papers and patents but, to the best of my knowledge, doesn't have one single video on his website or YouTube demonstrating how his product can save a pool owner money or how to clear up a cloudy pool faster than I can, for less money. I cleared this pool up in 2 days for $4.50:

There's no video that I can find that demonstrates him, using his product, clearing up a comparable pool in 1 day for $2.

Bottom line is this: I'd stick with sand if you're going to get a sand filter.


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