Sand Filter questions: issues with pressure?

[johnnyc]

Hi,

I have a sand based filter, when I switch the spider gasket to backwash mode, I only see dirt in the sight glass when the waste pipe is open, is this normal?

Also, I notice that when in filter mode, the filter jets start off strong, and eventually end up very weak after about 20 minutes. When this happens the pressure gauge increases until 1.5 bar, and stays there, is something wrong?

 

[Bama Rambler]

If you have a separate block valve on the waste pipe, then you won't see any dirt in the sight glass when it's closed. The sight glass is in a side stream off the waste stream and there's no flow through it unless there's flow through the waste piping. It will fill with water, but there's no flow through it.

What does your water look like? Clear, cloudy, green, etc.?
It sounds like you have algae growing and it's clogging the filter pretty quickly.

 

[johnnyc]

The water is clear, however the bottom of the pool has lots of small dirt which has accumulated over the winter, perhaps that is clogging up the filter?

When i was backwashing I still saw small black particles in the sight glass, even after about 3 minutes, should I continue backwashing until these disappear?

Also, when backwashing with the waste pipe open, the pool drains, I guess this is correct?

 

[pabeader]

Welcome!


It sounds like you could be in need of a good deep cleaning.
Here's a tutorial on the subject:Deep Cleaning a Sand Filter

Please post any questions you may have.

 

[johnnyc]

Thanks! 2 questions

When i was backwashing I still saw small black particles in the sight glass, even after about 3 minutes, should I continue backwashing until these disappear?

Also, when backwashing with the waste pipe open, the pool drains, I guess this is correct?

 

[Bama Rambler]

When you backwash you should run it until the sightglass runs clear. Now, does it have to be perfectly clear of every little spec, No. Mostly clear will usually do. It's your preference on how clear you like to see it.

Backwashing a sand filter removes water from the pool and flushes it out the waste pipe. That's how it rids the filter of dirt.