Sand and Debris from Filter in Pool

[rcsmitty]

I've got a 3 yr old pool and for the second time this week it pumped sand into my spa and pool. It seems to only happen when I switch it to spa mode. I've read all that I can on here, but I've got more research to do. I just wanted to see if anyone else had this particular problem. When I switch to spa mode it increases the pump speed and the pressure on the filter normally goes from baseline 18 up to 30 - this is the normal. I was wondering if there is anything that would fail under the higher pressures, but not fail at normal low pressure. My filter is a Pentair Sand Dollar it's the 80D, so it's large - holds about 350 lbs of sand. I've recovered about 10 lbs out of the spa and small amount in pool from when I switched it back to Pool mode. I ran out this morning to get a Spider gasket, and they sold me the whole plastic multiport piece with the gasket already glued in. I haven't put it in yet because I'm tired of cleaning the sand out of pool and it doesn't have a problem unless I turn the spa on. It's the first sunny day here in a while and I want to enjoy the pool instead of fixing it! When I vacuumed it this AM - I did vacuum to waste, so that I wouldn't get sand in the Laterals. Any ideas? Thanks!

 

[kimkats]

I hope you were able to enjoy your pool yesterday!

I don't really have any ideas but am giving you a bump to see if anyone else will see this and know what to tell you.

 

[zea3]

If the full speed on the pump generates too much force it can blow debris through the filter. Pull the key assembly from the old valve and compare the gasket on it to the new one. If the old one looks worn down install the new key assembly and see if you can reprogram the pump so it is not running full force in spa mode.

 

[rcsmitty]

Thanks! I'll try that!

 

[rcsmitty]

It wasn't the key assembly [emoji17] I guess I have a cracked lateral or standpipe. Another problem that started around same time is that the spa water level would drop overnight. I guess whatever is broken is causing the plumbing to lose vacuum/seal and allowing water to go backwards through the returns? Anyone have similar experience? I'm really dreading taking the filter apart and removing all of that sand! I've done it once before on a different pool and it's no fun.....

 

[kimkats]

SHOP VAC! That is my go to for taking the sand out. I have my big wheel barrow right there with the shop vac in it. When the vac gets full all I have to do is tip it over and start again. No lifting or such.

Good luck!

Kim

 

[zea3]

If you have any check valves in your plumbing examine them for debris that could be holding the valve open. The spa draining issue is probably unrelated to the sand in the pool issue. Spas that drain like you described either have a bad check valve or there is an air leak in an above ground portion of plumbing.

 

[rcsmitty]

Thanks! That makes sense.

 

[rcsmitty]

Thanks! That makes sense.

I searched over all of my pool plumbing and I cannot find anything that looks like any check valve that I can find a picture of on the web. I'll try to attach a picture taken during the build (a contractor did it). On another note, if I turn my multi-Port to Closed, the problem goes away. Doesn't this isolate the filter and suggest it is where I'm leaking? The water is going from spa (about 1 foot higher) back into pool. It's definitely going through the return and not drain. My actuators are working - they don't have check valves I don't think? I've got to tear filter apart anyway because of the sand going into spa, but it only does it in spa mode????

 

[zea3]

Water is siphoning through the spa jets (technically they are returns) into the pool. Someone else can probably explain this a little better, but somewhere in the plumbing there is an air leak that causes the plumbing to lose the vacuum in the line that holds the water in place, much like holding your finger over the top of a filled straw keeps liquid in it when you lift it out of the cup. Lifting your finger breaks the vacuum and the liquid drains out of the straw. Turning the multiport to the closed position prevents water from moving through the filter in either direction, so if water wanted to migrate from the spa to the pool it would not be able to flow past the closed multiport valve.

You could install a check valve on the return line between the filter and the heater. That should prevent the spa from draining into the pool. You can also try to identify the source of the air leak and fix that to correct the problem.

As far as the sand goes you will have to empty out the sand to inspect the laterals and stand pipe for cracks.