Draining excess rain water, sand filter has no waste setting.

MBPooldiy

Well-known member
Jun 14, 2022
64
Phoenix
Hi--recently moved to Phoenix and I am just getting familiar with the pool equipment that we've inherited which includes a Triton sand filter with a 2 position backwash valve. So I can either filter or backwash, there is no waste option. Since I have read that it is hard on a sand filter to backwash excessively, I am concerned about how to drain off excess rain water during the upcoming rainy season. Is it OK to drain a large amount of rainwater by backwashing or should I be looking to buy a separate pump to do that? The property is very flat so siphoning is not an option. Thanks!
 
Hi--recently moved to Phoenix and I am just getting familiar with the pool equipment that we've inherited which includes a Triton sand filter with a 2 position backwash valve. So I can either filter or backwash, there is no waste option. Since I have read that it is hard on a sand filter to backwash excessively, I am concerned about how to drain off excess rain water during the upcoming rainy season. Is it OK to drain a large amount of rainwater by backwashing or should I be looking to buy a separate pump to do that? The property is very flat so siphoning is not an option. Thanks!
Do you have a picture? I also have a triton sand filter and never heard of only a two position valve.

Backwashing will go to waste. It’s not hard on a sand filter to backwash it. The whole advantage of them is you can backwash it when it’s dirty.
 
Here are some pictures. This seems like a common backwash valve as I've found some Youtube videos on how to repair it. As shown, with the handle in the raised position the system is filtering. The water from the pool goes into the top filter port, out the bottom and back to the pool. When I want to backwash, I turn off pump then twist and push the handle down, re-lock then restart the pump. This closes off the returns so the water then goes into the bottom filter port, out the top to my backwash hose. At my previous home I had a multiport valve which I liked much better because I had a setting where I could just send the water straight to the backwash hose without going through the filter (it was a DE filter). I have actually been backwashing weekly for 5 min whether or not actually needed, just to keep the CYA down (but plan to switch to liquid chlorine as soon as I receive my test kit).
 

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That is a push-pull backwash valve, more commonly used on a D.E. filter (for D.E. use the handle is down and the bottom port of the valve is for waste/backwash, not return). You would see them on some sand-filter installs as they cost half as much as an MPV.

Most pools do not have an MPV, so a waste position is really a luxury if you have one. You could have a hose bib installed in the line from the pump to filter and use that to drain. It is very common to see those and you have a bit more control as the water won't come out as fast and the pool be lowered too much.
 
Unless you are using softened water for fill water due to evaporation, you will need a sump pump quite often to drain the pool to lower the CH. So buy one now. Amazon, Harbor Freight, etc. That and a length of hose and you can drain water when needed. The likelihood of having to drain water due to rain is very, very low. Unless your run off around the pool is into the pool, and then you will have bigger issues.
 
Yes, sump pump sounds like the simplest solution. I can see how that will eliminate any worries about whether or not I'm straining my filter by backflushing too much, or finding a pool plumber to change out valves or hose bibs. Thank you!

A slight nuance on the likelihood of having to drain rain water from the pool is that the likelihood will be high but only just a few times during our ~2 month monsoon season (if we are lucky and get lots of rain like last year). I did have a soft water hose bib piped from my house to the pool last summer and have been topping off my evaporation losses with softened water since then. For significant re-fills after backflushing, my plumbed in unsoftened auto filler also kicks in, but perhaps I will shut that side down for a while until CYA gets in range. I started with perfect water after RO filtration last spring and now CH is 300 while CYA is 183, based on Leslie's test. For me, CYA is a bigger problem than CH. I recently discontinued my weekly pool maintenance service that has gotten me to this point so that I can treat daily with liquid Chlorine and stop the trichlor tabs and shock. I had left the service completely on auto-pilot (or else why bother with the paid service) and I'm now playing catch up getting familiar with my pool equipment and water chemistry. Sure glad I found this site! I am hoping to bring down my CYA over time and avoid a complete drain due to all the water shortage concerns. But anyway I'm sure that I will initiate some other threads in that area once I get my test kit...
 
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