How often and how long do you backwash a sand filter

Hello,
I have a 30ft above ground pool with an EcoKleer 26" sand filter and 2hp waterway pump. This is only my 2nd season owning my pool, and I am not so sure when and how long I need to backwash my filter. Also, what about rinsing? When exactly should I use this process? I am just now opening my pool and I have problems with algae. I have used dang near a whole bucket of shock, a bottle of algacide, and I have crushed about (10-12) 3in chlorine tabs over the past few weeks. So far I still have a green pool. At one point it was a light blue color, but very cloudy. The problem I have been having is we have experienced such bad weather that by the time it is even close to being clear where I can vaccum it out, it rains and the water turns back to green. Last night I put 57 ounces of shock, and today it's still the same green color. I tested it, and of course my chlorine and PH level is low. I went and bought 3 gallons of bleach, but have used them yet. Also, my gauge on my sand filter is showing 40 psi. I backwashed it for about 3-4 minutes, and it didn't change much really. I just had the sand replaced a few weeks ago when I started opening the pool because I had a lateral broken on my filter. Is my gauge messed up, or am I just doing tons of things wrong?? I am sorry I am so clueless on things. Can someone please help with my issues? My kids are dying to get in the pool! Thank you for your time!

Hello, and welcome to the forum!!

First of all....when you turn your pump off, does your gauge go back to "zero". If not, then you're gauge needs to be replaced. You want to backwash the filter when the pressure rises 8-10 psi over your "clean" pressure. When you backwash, you do so until the water starts to clear up, and then with the pump off, turn it to "rinse" to flush the rest of the junk out of the lines. After rinsing until you're getting clear water, turn pump off again, and put it back on "filter".

We can help you get the pool cleared up, but we need to know your test results taken with a drop-based kit (no strips!!). Specifically we need to know your chlorine , pH, TA, and CYA levels--and whether or not you have any metals in your fill water (water from a well, or from city supply?). Once we know those things, we can help you figure out how high your chlorine level needs to be in order to kill off the algae. Shocking to kill the algae will involve raising your chlorine to a level that is determined by your CYA level (see the "best guess chlorine chart" link in my sig for more information about that) and then holding it there by testing and adding more chlorine as needed, until the pool clears. Don't put any more algaecide in it--chlorine is much better at killing an algae outbreak than algaecide is.

You really need to be able to test your own water and not rely on pool store testing for this...what test kit are you using? If it's strips, it's simply not accurate or reliable enough to treat an algae bloom. We highly recommend the K-2006 kit (see the link for testkits in my sig), or for now, if your local WalMart has the hth 6-way, it would work. At an absolute minimum, get the OTO kit (cheap kit that uses red and yellow drops for chlorine and pH).

What was the ingredient in the "shock" you used? cal-hypo or dichlor? And do you use tabs for your normal chlorine source?

Great, thanks for clearing up the backwashing process. I was never told to turn off my pump while switching up the process. Thanks so much for the information! Apparently, my gauge is broken because it goes to 30 psi when turned off. I will have to go purchase one of the tester you have mentioned because I have been using strips. I do have city water though. How do I figure out how many gallons my pool is? As far as the shock, it has cal-hypo in it. My normal chlorine source is the tabs. Thanks again for your time, and I will get back to you regarding the water testing.

How high are your pool walls? If we know that, we can guestimate your volume.

Welcome to the Pool Forum, by the way!

Thanks for the welcome! I believe my pool walls are 48, but I am not completely for sure. Now I am experiencing another problem. Yesterday evening, I decided to get in and vaccum it out hoping that would help get rid of the algae because I am tired of wasting my chemicals. Of course because the water was green, I couldn't see the bottom to assure I was getting everything; however, there were a ton of leaves that had settled in the middle of the pool at the bottom. I tried to get all that I could with what I could see, but now I am having a problem with my pump/filter. I don't know if it is clogged with leaves, but it seems as if my filter isn't working. You can hear the pump running just fine, but nothing is coming out of my returns. When I vaccumed the pool I did it on bypass to waste. I have tried backwashing, rinsing, and putting it on filter, and still nothing. I have done this several times, including cutting the pump on and off. So, I just turned it off and left it off. Any suggestions as to what could be wrong?

When you backwash have a white plastic pitcher handy. At first, the water coming out of the backwash hose will be brownish with lots of tiny bits and particles. After 15 - 20 seconds catch some of the water in the white pitcher and see how it looks. If it's still cloudy, keep it running. Backwashing my filter on a 12,000 gal pool takes about 45 seconds and a lot of water.

Rinsing packs the sand back down so it doesn't come shooting out of your return when you go back to the filter setting. I rinse for 30 seconds. Be sure you have plenty of water in the pool when you do this.

It doesn't really have enough pressure to backwash. When I tried backwashing it the water in the clear viewing tube was clear, but the water was coming out very slow. It seems like my filter isn't working. I don't know what is going on.

Does your pool have a skimmer basket? It may be full of leaves. And is there a pot with a domed lid attached to your pump? If so, it may also have leaves and will need to be cleaned out.