Making great water, the kind you can’t wait to get into, ultimately comes down to making the best choices among the available pool water treatment options. That can be tough because the pool and spa industry is loaded with various chemical products and devices that claim to be the best thing since canned beer.
The selection process becomes a challenge because unless you have experience with a given pool water treatment option, there’s really no way to know how effective it might actually be. That’s certainly true when it comes the type of filtration you choose. We have basically three primary categories of filter types used in pools and spas: sand, diatomaceous earth (DE) and cartridges. All three have their advantages and disadvantages and many people within the aquatics industry have strong opinions as to why they prefer one over the other two.
For the past several years, there is little question that cartridge filtration has become the choice for many designers and builders. Almost every set of plans I see these days from companies other than ours includes cartridge filters. Anecdotally speaking, it’s clear to me that this technology has become the most popular.
I’m writing this blog because I respectfully, but also strongly, disagree. Based on nearly three decades of experience servicing and building swimming pools, I believe cartridge filters are not the best choice. I’ll explain why, but first let’s look at the advantages that have attracted so many water quality professionals and consumers to these products that have, for better or worse, become water treatment mainstays.
Not So Fine Filtration
Perhaps the biggest selling point is that cartridge filters remove particles down to 1-5 microns, compared to 15-20 microns in a sand filter. Naturally, the idea of removing smaller particles to increase pool water clarity is very appealing. And it’s true – if you put a cartridge filter on a pool that has water quality issues, it will polish the water. Cartridge filters are not backwashed, so they also have the appeal of water conservation. And, they are easier to plumb than sand or DE, with no multi-port backwash valve – it’s just one line in and one line out.
For a long time, I didn’t disagree, at least not entirely. But, when I started looking at the issue more closely, rather than simply taking the product claims at their word, things changed. I started noticing more and more water quality problems in pools with cartridges, far more so than those with sand or DE, and the maintenance challenge of the necessary routine cleanings became a logistical nightmare.