What Valve Setting On Sand Filter Should I Use When I Vacuum My Pool?

by Lynn

When you vacuum the pool, what should the valve on the sand filter be set at? If I use the regular filter setting and have completed the vacuuming, I see green water shooting back into the pool from the return.

I asked the local pool co. what setting should it be on & their answer to me was "what setting does it work best on?"

I've tried using pump to WASTE but the water level goes down too fast to completely do the entire pool. So what setting & how do you keep the green from going back into the pool?

Thanks for the question Lynn

There are 2 settings that you can vacuum; FILTER or WASTE. As you already know, when you vacuum to WASTE the water level will drop.

FILTER is just that, dirty water goes in and clean water should come out. The questions says you're getting "green stuff" coming out of the returns. I would say this green stuff could be algae. I would ask what are the chemical readings, especially your chlorine level. It should be between 1.5 - 3.5ppm and the cyanuric acid (CYA) between 30 - 50ppm.

You may also have a couple of issues with your filter. Turn off the pump and open the sand filter. Check for channeling. This is when the sand becomes clogged with oils and debris. Water will find its way down the edges of the filter and be returned back to the pool as dirty water.

You can feel around the edges of the sand for holes, pits, etc. If you have channeling, you'll need to degrease the filter. It's easy to do, so email back if you have this problem. I can walk you through it.

If you have an algae problem, the best thing to do is shock the pool. Here are a couple of links for that:

Swimming Pool Chlorine

Pool Shock

And for clearing up a green pool:

Swimming Pool Algae

Green Pool Water

The links have chlorine charts for your size pool. It shows how much you need for a good pool shock. Try to go a little over the 10Xs shock, maybe up to 15ppm. It's better to go a little over then not hit the mark.

Shock at night and retest in the morning. Always give your pool 1 complete turnover before making another adjustment.

Pool Opened By A Company On Monday -- It's Still Green Water On Thursday!

Shocked The Pool & Still Having Swimming Pool Algae

Look over these pages as well. The first one has a slight legal issue, but your can disregard that and just focus on the algae problem.

Be sure you have enough sand in the filter.

Change The Sand In Above Ground Pool Sand Filters

Be sure to read the entire page.

Hope this helps and have a great swimming season.


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Jan 10, 2015
Green Algae In Pool And Vacuuming
by: Anonymous

Usually I vacuum on filter setting. When done I backwash for about 2 minutes or until the water runs clear, then turn on the rinse cycle for about 1 minute.

We had the same problem for a couple of years in a row with green algae, tried to figure out what we were doing wrong cause it was getting expensive going to the pool store and buying alot of chemicals week after week.

The main thing that we figured out is to ALWAYS make sure you have chlorinating tablets in the skimmer basket or feeder at all times, this way the pool is constantly being treated and #2 shock the pool once a week.

If you have heavy bather loads or the pool is too warm it introduces the algae if you are not chlorinating constantly.

You must scrub sides and bottoms of the pool to rid it of the algae, fill your pool as high as you can and turn the filter on waste as you vacuum (try to not go slow) the suction on waste is much better than on filter setting, when done backwash till water runs clear and then rinse for approx 1 minute.

We have owned a pool for years and the only reason we had an algae problem for those couple of years was because of lack of maintenance, we have been algae free for a couple years now cause we make sure the pool is always being chlorinated.

Also, when you add the pool shock, slowly pour it in the skimmer basket while the filter is running and you can also broadcast the shock around the pool in areas of heavy algae.

I would also recommend to clarify the pool as this will coagulate any debris and drop it to the pool floor, then vacuum as usual.

Hope this helps

Jan 10, 2015
Sand Filter Vacuum
by: Anonymous

I always vacuum with it set on filter. When I am done I switch to backwash till the water runs clear. This should clean out your filter.

May 23, 2014
Losing Too Much Water?
by: Anonymous

FYI...if you throw your water hose in pool at the same time as your vacuuming and add water this can help...i put mine around bottom edge...it helps give me a little more time to vacuum.

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