I have a 250-gallon Fantasy Splendor spa that gets pretty heavy use, probably average 45-60 person-minutes per day. I've had the tub for 2 years. My standard filter cleaning regimen has been to "deep clean" the filter when doing refills, which are done once every 2-4 months. This is the only time I clean the filter. Steps are:
Questions on filter chemistry and replacement protocol:
- Run the filter under a bathtub tap while slowly rotating it and spreading each pleat open, going a full 360 degrees. Takes maybe 10 minutes. If I see a particularly dirty pleat, I'll scrape it out with a gloved finger. A lot of Crud washes out, but nowhere close to all of it, particularly the debris toward the end caps, where the pleat can't be opened very wide and water can't easily reach.
- Soak the filter for 12-24 hours in sodium triphosphate solution in a ~10-gallon bin-- about 1 cup granulated sodium triphosphate per 10 gal water. The water quickly develops a gross, murky, slightly yellowish color.
- After the soak, thoroughly rinse out the filter to get rid of any phosphate, then reinstall in fresh tub.
Questions on filter chemistry and replacement protocol:
- My understanding is that the purpose of the filter is to remove large-ish (i.e. visible) particles. Dissolved chemicals and tiny particles presumably pass through the filter pleats (even if slowly), and must be degraded by chemical oxidants (I use dichlor/bleach method). So, the only "failure mode" of the filter would be when it is so clogged with Crud that it negatively impacts water circulation and/or overloads the pump. I have seen no sign of this at all, and my described cleaning regimen seems sufficient to keep it from ever happening-- it has no problem rinsing out most large debris. But in "general maintenance"/"best practice" articles for the layman, I see it recommended that I replace the filter every year or so. But why, if it isn't impacting water circulation? What are the implications of using a filter for a very long time?
- Related to question (1), what does the discoloration of the filter paper/fabric mean? What causes it? Is it merely cosmetic, or is it directly tied to something impacting filter performance? Is there any way to restore it to white, and would that reverse any impacts on performance?
- What are the effects of 'deep-cleaning' the filter with a soak in sodium triphosphate or detergent/some other cleaning fluid? Doesn't this get microscopic soils out of the filter medium? Is there something better than sodium triphosphate (I believe I adopted this because of a ChemGeek recommendation in another thread)? Washing clothes in a washing machine can remove very heavy soils-- you can sweat buckets into a gym shirt every day for years, and it will still come out of the wash smelling fresh every time, though colors will fade. The lifetime of the shirt is determined by the physical integrity of the fabric, not some build-up of impossible-to-extract soils. I would think that pleated hot-tub filters would function on the same principle, given that they are (1) also made of a kind of fabric; (2) not subjected to more heavy soil than the aforementioned daily-use gym shirt. But the advice to regularly replace the filter suggests otherwise. What gets stuck in the filter that can't be removed through a detergent soak (and physical blast of water)?
- I find it a pain in the butt to clean out the individual filter pleats as described in my cleaning regimen. It is also an imperfect process that leaves a lot of gunk near the end caps. Why are these things so difficult to clean? Is there a filter on the market where I can remove and flatten /unfold the filter medium for easier cleaning? Or keep the cartridge but replace the medium? Or some other filter design that's easier to clean?
- I've seen that there are ceramic and diatomaceous earth filters sometimes used, but all the use-cases I've seen have been for pools. Are these appropriate for spas? Why or why not? If so, what are the pros and cons vis-a-vis pleated filters?