Howdy to all...summer's almost here! That means it's time to try to resolve an issue from last year.
Since I've had this pool, the clean filter pressure has been 29 psi. The weird thing is that the pressure never increases, it only goes down...mostly because of the pump strainer basket as there is a forest of pine trees right next to the pool and all those needles fit through the holes in the skimmer baskets & main and get caught up in the pump basket (or impeller ) But it also goes down when the filter gets dirty...it goes back up after backwashing.
I replaced the sand in my filter early last year because it didn't seem to be filtering very well and we had bought the property with no history other than we knew the pool had obviously been installed for at least ten years.
After cleaning the laterals - the slots were completely jammed with grains of sand in them - I replaced the sand. I began to get little piles of sand building up in the pool under the returns. At first I thought maybe it was just washing out the new sand that was fine enough to fit through the slots and would dissipate. It did improve some by the end of the season, but not completely and the water still wasn't as clear as it used to be (but had good chemistry) I was attributing that to the excess sand getting pumped back in.
But after pondering it for a bit, I'm wondering if the sand is making it past the lateral slots because the pressure is so high that it is forcing sand through them...perhaps it didn't do that with the old sand because it had been thouroughly "rinsed" of all the finer particles and those grains that were jamming the slots effectively reduced the size of the slots. Long story less long... after replacing the sand, the clean pressure stayed at 29 psi.
Another tidbit...I have a SWG cell that is installed downstream of the filter. Somehow, a small amount of pine needles and other debris (dog hair, small bits of various organic clutter) manage to get past the filter and lodge in the plates of the cell. It's not a huge amount, but enough to warrant cleaning it about every six weeks. I took the top of the filter off and the sand looked normal - no channelling or bio-mat.
I was VERY careful when putting the new sand in the filter - put water in first, SLOWLY poured the first couple of bags in and CAREFULLY bedded the laterals down, so I would be very surprised if I broke something.
I have a 1 1/2 hp A.O. Smith pump motor, but cant find any data tag or number or anything on the pump itself.
I thought about reducing the pump size, but with all of the organic load the pool gets, and the fact that it's a very weird shape, I need all the circulation I can get - I keep it running 24/7 and still have a hard time with debris on the bottom. If the pump is in fact too big for the filter, does anyone have any thoughts on adding a second filter in parallel with the first? Maybe a different media - to increase filter capacity while reducing the pressure and keeping the flow up.
So to clarify, my questions are:
Why am I getting sand through the returns?
Why is the pressure so high?
Why doesn't the pressure increase when it needs a backwash?
Is adding a second filter in parallel a good idea?
I'm just getting ready to open the pool - we had over a foot of snow and fifteen degrees a couple weeks ago and even with the cold spring we've had, I've got a swamp again...sigh. I figure if I'm going to change the filter set up, I might as well do it now.
Sorry for the and TIA and for all the past help just with the plethora of great information...the PS guys don't like me anymore because I quit buying all their stuff when you all taught me the right way to take care of a pool!