I'm going to be moving my pool equipment later this summer when I build a poolhouse. I'm considering some changes to try to avoid having to add so much water due to backwashing. I live in a very rural area, so I have a significant debris load after storms or periods of wind. For this reason, I chose a sand filter, and still believe it is my best option. I also have well water that has seriously high alkalinity (I've measured it as high as 800). I used Ben's aeration method last summer along with a mesh cover to allow maximum rain water dilution over the winter to lower my initial alkalinity from about 280 down to 180, but adding well water to top off after backwashing could drive it back up. Here are my thoughts and ideas:

1. Truck in fill water. I have a trailer that could be dedicated most of the time to holding a tank, and the 280 TA water is available reasonably cheap. I'd still have to fight alkalinity, but not as much as with my well.

2. Install some kind of filter in the backwash line and return it to the pool. I've looked at the polishing bags, and if they work as advertised, they might be an answer. Wouldn't be quite as convenient as something plumbed in. I've also even considered getting a cartridge filter to use strictly to clean my backwash water. Downside here would be the added cost and cartridge cleaning required, but I would in effect have all the good things about a sand filter and a cartridge filter, but only the cleaning disadvantage of the cartridge to deal with.

3. Plumbing an extra suction line with a valve to let me backwash with tanked in water. This way I'd close the drain and skimmer valves, open the extra intake that would be connected to the tank, and backwash. This water would never go in the pool, and already balanced and chlorinated pool water would stay in there. I'd only have to replace evaporated water.

4. (The odd one) Plumb my well into the inlet side of the filter, so I could run well water through the filter set on backwash then rinse with the pump off. Same benefits as #3, saving me hauling tanked water. Net water usage is no more than I go through now, because I have to replace what goes out for backwash anyway. Unknown is whether I will accomplish any or enough cleaning with the reduced flow this method would provide. An added benefit would be that I could then add fill water via the returns and wouldn't need a hose. More complexity for winterizing though.


I'd be interested in any comments folks have. I'm considering trying #4 just because of the simplicity and the fact that it would be pretty reversible if it doesn't work. It might even be able to just reduce my backwash water usage.

Thanks,
John