- Nov 15, 2018
- 188
- Pool Size
- 19000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Monarch ESC24 / ESC7000
A story about a careless filter installation :
Back in December 2020, I was next door having a beer with the neighbour when the kids came screaming in "daddy, daddy the pool filter has split". My trusty 21 year old Onga Pantera polycarbonate sand filter had popped a seam. I tootled off to the local pool shop to buy a new one. I have a 19kl pool and a 3/4hp pump, so I need the smallest sand filter they reasonably sell or I can't get the water flow to do a proper backwash. They had one filter small enough in stock, and so home I went with a new Davey.
I opened the box to find it missing the pipe fittings. Back to the shop to be told that was the only one they had and the next one would be due in January. Instead, they gave me a complete replacement valve. This valve is suitable for most Davey sand filters (at least the ones larger than mine). It didn't fit. Specifically it didn't fit because it sat too deep inside the filter and the stand-pipe on the laterals was too long. The shop said "nothing I can do, do whatever you want/need to make it fit and we'll still honour the warranty", so I trimmed the stand pipe. In my haste, I thought I might have trimmed it a bit short but it worked and got us through summer with the kids swimming every day.
Cue a catastrophe which saw us not touch the pool for 6 months and it got ignored. Pool was clear and blue, but not seeing a bather over winter.
Now we're back in summer. Pool has been a whisker cloudy after some heavy use, but when I put the pool cleaner in it cleared right up. Christmas Eve and Christmas Day saw 4 kids in the pool for 6 hours both days, plenty of sunscreen, confetti, water balloons and whatever else comes out of kids who don't want to get out of the pool. This morning it looked like soup. Blue soup, but soup. I figured it just couldn't be filtering properly and I had a note I made when I installed it that the stand pipe might have been marginally short (I was in a big hurry).
The valve has a pocket in the bottom that is 48mm deep for the stand pipe. There is an O-ring some 18mm into the socket. When I switch on the filter, it grows. The valve moves upwards as the water pressure expands the shell. What had been happening was the filter worked fine when the pressure was below ~60kpa, but above that the shell grew sufficiently that the stand-pipe dropped below the o-ring acting as a pressure regulator and bypassing the media. No matter how dirty the filter was, the pressure never exceeded 60kpa. With the pool cleaner in, the suction restriction kept the pressure below 60kpa and it filtered properly. Without, and with dirty media it bypassed most of the water.
I had some time this morning, so I popped the valve off and measured it all up to find the stand-pipe was 18mm shorter than it really should be (probably only needed another 5mm, but lets do it properly). The filter shell was growing ~12mm and that was just enough to bypass. I syphoned the shell, cut the stand-pipe and extended it with a 40mm in-line joiner. Glued it up and let it set. 5 hours later the pool is clear and the filter pressure is higher than I've seen it since I installed the filter.
Careless Brad. On the flip side, because it and the media was new it got us through last summer, and that was really all that mattered. If you are going to modify hardware, measure twice and cut once!
Back in December 2020, I was next door having a beer with the neighbour when the kids came screaming in "daddy, daddy the pool filter has split". My trusty 21 year old Onga Pantera polycarbonate sand filter had popped a seam. I tootled off to the local pool shop to buy a new one. I have a 19kl pool and a 3/4hp pump, so I need the smallest sand filter they reasonably sell or I can't get the water flow to do a proper backwash. They had one filter small enough in stock, and so home I went with a new Davey.
I opened the box to find it missing the pipe fittings. Back to the shop to be told that was the only one they had and the next one would be due in January. Instead, they gave me a complete replacement valve. This valve is suitable for most Davey sand filters (at least the ones larger than mine). It didn't fit. Specifically it didn't fit because it sat too deep inside the filter and the stand-pipe on the laterals was too long. The shop said "nothing I can do, do whatever you want/need to make it fit and we'll still honour the warranty", so I trimmed the stand pipe. In my haste, I thought I might have trimmed it a bit short but it worked and got us through summer with the kids swimming every day.
Cue a catastrophe which saw us not touch the pool for 6 months and it got ignored. Pool was clear and blue, but not seeing a bather over winter.
Now we're back in summer. Pool has been a whisker cloudy after some heavy use, but when I put the pool cleaner in it cleared right up. Christmas Eve and Christmas Day saw 4 kids in the pool for 6 hours both days, plenty of sunscreen, confetti, water balloons and whatever else comes out of kids who don't want to get out of the pool. This morning it looked like soup. Blue soup, but soup. I figured it just couldn't be filtering properly and I had a note I made when I installed it that the stand pipe might have been marginally short (I was in a big hurry).
The valve has a pocket in the bottom that is 48mm deep for the stand pipe. There is an O-ring some 18mm into the socket. When I switch on the filter, it grows. The valve moves upwards as the water pressure expands the shell. What had been happening was the filter worked fine when the pressure was below ~60kpa, but above that the shell grew sufficiently that the stand-pipe dropped below the o-ring acting as a pressure regulator and bypassing the media. No matter how dirty the filter was, the pressure never exceeded 60kpa. With the pool cleaner in, the suction restriction kept the pressure below 60kpa and it filtered properly. Without, and with dirty media it bypassed most of the water.
I had some time this morning, so I popped the valve off and measured it all up to find the stand-pipe was 18mm shorter than it really should be (probably only needed another 5mm, but lets do it properly). The filter shell was growing ~12mm and that was just enough to bypass. I syphoned the shell, cut the stand-pipe and extended it with a 40mm in-line joiner. Glued it up and let it set. 5 hours later the pool is clear and the filter pressure is higher than I've seen it since I installed the filter.
Careless Brad. On the flip side, because it and the media was new it got us through last summer, and that was really all that mattered. If you are going to modify hardware, measure twice and cut once!
