backwash water goes into pool

I have a sand filter and noticed that after every time we backwash, the pool looks a lot worse. I've actually watched brownish water flowing INTO the pool while it is being backwashed. This is more than just a little sand, I mean the whole pool is cloudy after we do it. I don't see how this can be right, but in my ignorance, I've never done anything about it yet. Just try not to backwash very often.

I'm currently fighting and winning the battle against what I believe to be some serious mustard/brown dust algae, thanks to the help I've gotten here. I'm dreading backwashing the filter, which needs it soon, because the pool will be brown again for a day or two! We have followed the procedure in the manual EXCEPT opening the air release valve at the beginning of the backwash procedure. Would that cause the problem or do we have a plumbing error?

Bless The Pool Forum. I feel I finally have a grasp on all of this!

Ouch! Something is plumbed wrong or assembled wrong!

What brand and model of pump, filter and multivalve do you have, and what kind and size pool?

Your multivalve should have 3 openings large openings: From the pump, to the pool, and backwash waste. They should be marked on the valve. If they are correct it's possible the multivalve is assembled wrong, such as with the spider gasket incorrectly placed, or the wall between two chambers in the valve broken. Unless there's something esoteric going on, that's your most likely culprit. I'll let the folks who are more expert on multivalves give a better explanation

Stats on our situation:
11,940 gal. Pebble Tech pool. New 1 hp Sta-Rite Dyna-Pro pump (we had this problem before the new pump was installed). The filter is a Sta-Rite high rate sand filter model hpb24, 3.1 sq. ft.. We had the sand changed out a couple years ago. We have a Hayward Pool Vac Ultra in the pool, too.

Next week, we have a service coming to change the way the filter discharges backwash water. The former home owner had it plumbed to drain into the common area of our subdivision which is a big no-no. They are going to put a regular hose in (I guess) so we can be legal and drain on our own property. I was hoping to figure out this plumbing thing before they come next week.

Thanks a lot!

In an effort to answer your question, how much water is going back into the pool when you backwash? Does it gush, or is it a trickle?

I had a similar issue on a different brand name sand filter. When I ran the filter in the normal filter mode, a trickle of water would discharge from the backwash hose. My problem was the spider gasket inside the valve. Once I replaced it, all was good.

Unless a huge error was made, as Carl suggested - I think BTDG has hit the nail on the head. Open upi the top of the multi and see how the gasket (spider gasket or wagon wheel) looks and d the channels it sits in.

If you need help figuring out what you find inside the multi, you can search some of the old threads or just ask us.

Welcome to the forum!

OK, let me clarify and amend my question. We just backwashed and I watched what happened. No water went into the pool during backwashing, but when we turned it back to regular filter mode, lots of cloudy water went into the pool. We don't have a "rinse" option. Do we just need to let it backwash longer? Doesn't seem like cloudy water should go back into the pool as badly as it is. Our entire pool now looks milky and it was clear before :(.

Is there a clear sight glass that you can watch until you are sure it runs clear? No rinse option? Do you have the manual that came with the filter or if not, maybe you can look online and see if you can find it?

We do have the manuals for all the equipment, but it never mentioned a rinse option and it's not marked on the equipment. The only "sight glass" is a crummy old piece of semi-transparent hose they installed as part of the backwash pipe. I don't think you could really see through it well enough to decide when to stop backwashing. We usually stop when the pressure is back to starting level of 10.

As I said, there is a person coming to give us a regular backwash hose, so maybe that will help us be able to monitor the water that is coming out better. I'm going to ask that person's advice on this problem, too, however I've started to distrust some of the professionals in the pool industry. That's why I am asking here first! Thx...

One simple way of telling when the filter is clean during the backwash operation is to catch some water in a white plastic pitcher. When you see few or no particles, you're done.

That there's no rinse setting on the filter is odd. Backwashing pushes water into the bottom of the filter and really stirs up the sand. The rinse cycle then packs the sand back down. From my own experience I know that if I didn't rinse for 30 seconds I will get some sand in the pool.

That is what I am concerned about, too. Even when they think they have the water coming out the backwash hose looking clean, I'm afraid they will still get a blast of sand back into the pool. Maybe call the filter manufacturer and ask them about this problem?

I was thinking maybe it would help to wait 20-30 minutes to let everything settle down inside the filter before turning the pump back on. I don't know... I will ask the pool guy and let you know what he says. Thanks!