Backwashing according to pressure gauge or not?

[sparkwatercleaner]

Thank you Larry.

To open the filter, I will need to unscrew the pipes attached to the multi port valve, but I have no experience in doing this, and the screws seem to be sealed with glue. What should I do?
Sand came out from the filter the first 4-6 times I backwashed, now sand isn't coming out when backwashing or is either a very small amount of it. I told the pool guy about it but he said it's normal... huh.
Starting pressure decreases slightly every time I backwash.
According to you, I should get a new and bigger filter? (I'm not willing to spend a lot of money...)
What confuses me is that pressure never rises the "green" part of the gauge, nor it did when I ran the pump with the multiport valve closed.
I run the filter 6 hours a day and it seems to do the job, thew pool just gets slightly cloudy when it is used by many people.

[Larry]

Sand came out from the filter the first 4-6 times I backwashed

This can be expected in a new filter, when we tend to overfill slightly and the new sand hasn't had time to settle yet.

Starting pressure decreases slightly every time I backwash.

Could indicate ongoing sand loss or calcification of the sand resulting in "channeling".

According to you, I should get a new and bigger filter?

You mention that the pressure stays in the green - you do not need to change the filter. The pump/ filter specs seem a little off but it sounds like your setup is OK.

What confuses me is that pressure never rises the "green" part of the gauge, nor it did when I ran the pump with the multiport valve closed.

If you want to make sure the pressure is rising, don't close the 6-way valve. Try closing the valve on the return line to see the increase in backpressure. Never close it all the way or you risk bursting the filter (it's only blow-moulded after all).

To open the filter you need to unscrew the collar holding the multiport valve onto the filter. If there is not enough play in the pipes you will have to remove the multiport valve to get to the sand, but it sounds like there are no threaded unions for easy opening. I would ask the people who put the pool in for guidance to remove the multiport valve.

[sparkwatercleaner]

My fears have come true! Sand is STILL coming out from the waste line when I backwash. I've just noticed it. It is almost a handful of sand. Also, the pressure gauge shows less starting backpressure than the last time I backwashed. These means just one thing: that the pump is oversized for the filter, right?
I'll contact my pool builder. The filter and pump are both under warranty, so I expect him to do something.

[Larry]

I would guess the filter is too small for the pump.

The other possibility is someone forgot to put the diffuser head on the center pipe (if your filter comes with one), or you could add a diffuser to see if it helps.

When the pump is too powerful, the pressure guage tends to be high initially; do you remember if the pressure guage was always in the yellow/ red in the beginning?

[sparkwatercleaner]

When the pump is too powerful, the pressure guage tends to be high initially; do you remember if the pressure guage was always in the yellow/ red in the beginning?

No. That is what confuses me!!! It was always pointing the beginning of the green part!!!