Is this normal? This can't be normal

[joshrogan]

For the second year in a row, I'm pretty sure I'm doing something wrong while opening the pool.

We have a 23,000 gallon pool with a Hayward EC65A D.E. pool filter (the kind with the fins, not the cartridge) and a variable speed pool pump.

I opened the pool yesterday. pH was perfect, put in some baking soda to raise the alkalinity to 110ppm, and then put in 10 pounds of 63% shock.

Here's where things seem to be going wrong.

When I turn on the pump, everything is fine and dandy. Good strong water pressure coming out of the two jets, good suction into the filter basket. Add 6 pounds of D.E., and it looks good. I'm running the pump at 3000 rpm.

When I check on it a half hour later, there's barely any pressure coming out of the jets. The filter pressures reads 16 -- it's a little lower than the green line at 20, but not super low.

I bump the filter handle 20 times, and the pressure comes back to the jets.

Half hour later, it's dead again.

Is this normal for pool opening, while it's clearing out all the algae? Or should it run longer than that before the pressure dies?

Here's what I've tried:
(1) I've tried fully flushing and re-filling the DE from the filter. Again -- lasts 20-30 minutes of strong pressure before it dies off again.
(2) I've checked the skimmer basket and pump filter basket -- both fine.
(3) I felt up into the impeller, but didn't feel anything. I didn't take it apart, though.
(4) I'm thinking it's unlikely that this is a clogged pipe because the pressure gets stronger after bumping the filter. I would think if it were clogged it would be weak all the time.

I really appreciate any advice anyone can give, as I'm sure I'm doing something wrong!

[Denniswiseman]

That does seem normal, you probably have an algae bloom that is clogging your filter and you need to Slam
You say your pH is fine but let us have a complete list of numbers and TA of 110 is not necessary
How do you test?
FC:
TC:
pH:
TA:
CH:
CYA:
My pool construction:
Pool chemicals:

[joshrogan]

Hi Dennis - here are my numbers, I test using a Taylor kit with the droppers:
FC: 17ppm
TC: 0
pH: 7.4
TA: 150
CH: 390
CYA: 60
My pool construction: Vinyl liner, 23,000 gallon pool with a Hayward EC65A D.E. pool filter (the kind with the fins, not the cartridge) and a variable speed pool pump.
Pool chemicals: not sure I understand the question?

The pool isn't green any more after two days of pumping, but it's still cloudy. I brought it up to 30ppm twice, and now it's back down. The filter is still slowing to a trickle after every 30-60 minutes, and only goes back up after I bump the handle on top.

Thanks so much for the help!

[Denniswiseman]

Your numbers seem OK except you haven't given your combined chlorine
With a CYA of 60 you need to slam at 24ppm of chlorine but that must be maintained (SLAM Shock Level And Maintain) keep going twice isn't enough
Have you red the Slam instructions
Chemicals means how do you chlorinate reduce pH and TA and increase

[joshrogan]

Yup - we're in the middle of doing that now. I'm just surprised that the pressure drops so low every 30 minutes or so.

[Denniswiseman]

That is all the dead algae being vacuumed
It will get better, some people take weeks to get it right. Keep testing, brushing and chlorinating till you past all three criteria
You are done when:
CC is 0.5 or lower;
You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
And the water is clear.