The universal recommendations for backwashing Filox (aka Catalox) are like doing oil changes: based on time as well as usage. I never understood why I'd have to change the oil in my car every 3 months whether I drove it or not, and similarly I'd like to understand why Filox needs to backwashed every couple of days regardless of how much usage it's getting. Anyone know?
It's a bit disconcerting to think that I might only draw a couple hundred gallons of use, and then have to spend 120 gallons to backwash the filter.
Maybe an example will help clarify.
Case A: Daily use is about 300 gallons a day. Tank size is 10x54, 1.5cf of Filox. Recommendation: Backwash every other day.
Case B: Daily use is about 75 gallons a day. Tank size is 10x54, 1.5cf of Filox. Recommendation: Backwash every other day.
If Case A says that after about 600 gallons I should do a regen, then in Case B I should be able to go a week between regens - but that's not the recommendation. There's some kind of time element involved that's independent of actual gallons used. If the time element is an approximation for number of start/stop water flow cycles, that would be interesting to know and then to understand the physics involved would be the next step, but I'm doubtful. It's more likely that the material bonds to itself over time...
So, my question still stands - what non-usage-related thing is causing the recommendation for frequent regeneration of filox/catalox media?
Some sediments get hard if they sit too long. Then, you can't wash them off.
On cars, one thing that can get them is moisture. Humidity and pressure changes can draw moisture in, and if the car is not run often enough or long enough, rust or oil failure can occur. The vapor recovery of modern cars is better than the old ones, but it still can be an issue. They used to be open to the atmosphere with a filter, now they have a carbon vapor recovery system, but that's mostly for the gas tank, not the engine oil breather. If you drive a car long enough, often enough, you can probably safely extend that change interval, but zero miles could still be a problem; a reasonable trip once a week or two would probably eliminate any buildup and prevent problems.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013
Time causes the dirt to build up, dry out (yes even underwater) and otherwise stick to mineral particles making it harder to remove if not impossible. So it accumulates on the mineral reducing it's filtering ability other than mechanical filtering; like an oxidation type filter for H2S, iron or manganese etc..
My opinion comes from doing water treatment for 24 years now which is a bit different than you wanting things to work differently than they actually do. So you use 120 or fewer gallons of water to operate your filter that is being used to greatly improve the quality of your water. So what, take fewer showers, wash veggies quicker, wash the car once a year if needed.... we use water for many things we really don't need to do, like watering the grass in a desert! DUH! It is what it is if you want good water.
I'll back that post
Perception is 3/4 of reality