Pressure just builds......

[ajwray]

Opened the pool two weeks ago. 16x32 IG. At first would not even get suction so I replaced the O rings on the Hayward valves coming from the skimmer/main drain and also on the two port valves. This usually is my problem after the winter and that fixed the suction problem.

I have a Hayward DE filter with a multiport and grids. The filter pressure rises after a few hours. I take out the grids, clean them and for about two hours the filter will run at about 15 psi and then slowly work its way up to 24 psi which then releases a low pressure stream from the outlets to the pool. Backwashing doesn't get the same effect as removing the grids but again after two hours I am back at where I started. I only put in a 1/3 of the regular amount of DE to see what was happening but even that stops after two hours. A day later the pump basket is only filling 2/3 of the way. The pool was green when opened (very warm January, lots of rain here in the Northeast) but is now just slightly cloudy (you can almost see the main drain in the 8FT end). Any suggestions? I'm thinking it's either the grids (can they go bad and just get permanently clogged, they are at least 7 years old) or perhaps the multiport gasket.

[duraleigh]

You must get rid of the algae in your pool. Almost surely your filter is being clogged because of the algae.

Post a set of test results (FC, TC, pH, Alk, CYA) and you'll get lots of good help.

[waste]

AJ, welcome to the forum. I'm almost positive that Dave is correct in his assesment, algae will clog a de filter very quickly (the reason being that individual algae cells are ~the same size as the filtering channels in the de). However, the grids may have accumulated oils or calcium build up over the course of 7 years, in which case a TSP bath and an acid bath may be in order.
Do you have sufficient water, both in the pool and available to refill the pool, to do your vacuuming to WASTE ?(no relation to me) As Dave said, getting rid of the algae should be your priority. If you need any help with the algae removal, take a look at the "Dealing with algae" section of this forum. Good luck and keep us posted - should you need any more help, just ask, some of us live for this stuff

[ajwray]

Thanks,

I thought it might be algae as well at first but I'm not so sure now. When I opened I put in 5gal 12.5% brushed the sides, vacumed to waste, then opened the filter, cleaned the grids. Works for two hours. Next day repeated the above minus the 5gal. Works for two hours. Next day another 5 gal vacum to waste, clean the grids (which were not green at all) and then worked for two hours. Daily after that cleaned the grids, let run.

Algae was my first thought as well but it's never taken this long to clear in the past, (first time when we bought it and another when the squirrels ate through the cover). I am on my way to the local pool store to get some fresh chemicals for my testing kit and will post those asap.

I have been around this forum for a while but this really is the first time I have had problems, the help in a friendly manner that everyone gave is really appreciated.

[ajwray]

CYA 36
TC 3
FC 3
PH 8.2
TA 109
HARD 140

Realize I have to bring the PH down. I am also going to chemically strip the filter today.

Any other suggestions??

[waste]

Use a detergent or TSP to get the oils off before acid washing the grids.

[ajwray]

Waste...thanks for the advice. It's soaking right now in TSP overnight. In the morning I will rinse well and then do the acid.

[ajwray]

Status Update: The water is almost totally clear but the grids still only go about three hours then I backwash and they need another three hours. Then backwash. I did the TSP soak overnight. Then the acid soak overnight. Vacumed to waste. Current test results:

TC 3
FC 3
PH 7.6
TA 109
CYA 36


20k gallon 16x32


Any other suggestions? Maybe time for new grids (they look fine)? The suction and return lines are fine because the pressue is even when on recirculate.

Help!! I'm selling this house in two weeks and don't want to spend too much more money for a pool I'm not going to enjoy.

[waste]

AJ, what model filter do you have and how much de do you add after backwashing - also what is your backwashing proceedure? (The reason I ask is that there have been a few people recently that have had similar problems due to improper backwashing/ recoating). One last thing, does de come out of the return jets when you recoat the filter?

[ajwray]

Waste, thanks for your continued help...

1. It's a Hayward DE-3600. 36 Square foot grids.

2. I turn off the pump. I hook up the backwash hose. I put the multi-port on backwash for at least 3-4 minutes. Typically, I will wait 1-2 minutes after the little jar on the valve is clear. I turn off the pump. Set the pump to rinse for a minute. Turn off the pump. Set the pump to filter. Add 4.5 lbs of DE through the skimmer.

**I haven't been using the whole 4.5 yet as it was stopping flow. I have been using about half of that does before the pressure builds.

I hope this helps you to help me and hopefully solve the mystery. Right now the pool is clear as anything so something good is happening. There was a lot of dirt (debris) on the bottom not that it was clear and I vacumed that out to waste today which cleared it up even more.

3. No DE is coming back into the pool through the return jets.