Green Cloud out of my Sand Filter

[Knucklehead]

We just got through winning a battle over green Algae. The pool started to turn dark and it clouded a bit. We started hitting it with Chlorine to shock it and now, after about a week, it is just getting crystal clear again. Everytime I turn the pump up to vacuum I get a green cloud of what I think is algae. I backwashed my sand filter once during this process. I suspect the answer is that if I'm fighting algae, I should backwash after each vacuuming of the pool. Am I right in this? Do I have a Sand Filter problem? Below are my essentials as of a few days ago...

FC = 7.5
CC = 0.0
TC = 7.5

CYA = 50

TA = 300 (down form 450, it has been steadily dropping as I keep adding Muratic Acid to keep the pH down)

CH = 270

 

[MassNerd]

Well, I can tell you, you aren't the only one who experiences the "cloud" from your sand filter. I'm a new pool owner and also noticed that when the filter is dirty, even just partially, I get a cloud out of the returns for the first couple seconds. This is after the pump has been off for some time and I turn in on to high speed. If the filter is clean, no problems. More incentive for me to backwash often I guess. I was wondering if something was wrong with my filter though. Glad you asked.

As far as only backwashing once during the whole SLAM process, I'd guess yes, your filter is very dirty and needs a backwash!

 

[techguy]

If you finished the war, did you do an OCLT where you test the FC before bed and the next morning (pump on) to see if you had killed off ALL of the algae? Sounds like you have some left in the filter and in the pool.

Time to SLAM again! You were Soooo close.

 

[duraleigh]

Are you "rinsing" after the backwash cycle?

 

[MassNerd]

I am. Till the rinse runs clear for 10 seconds. Usually rinsing takes <30 seconds total.

 

[Jeetyet]

I am. Till the rinse runs clear for 10 seconds. Usually rinsing takes <30 seconds total.

The S244T manual says to rinse between 30 secs to 1 minute so you might want to adjust your rinse time slightly. I have the same filter and fought the same problem of cloudy water blowing back at pump startup for much of last year. What I did that may have finally resolved the problem was to do multiple backwash/rinse cycles each time I needed/wanted to backwash. (You might would be surprised how dirty the water in the sight glass looks, again, if you redo a backwash right after you're done with your normal cycle) Instead of running on backwash until the sight glass was clear then rinse, I would run backwash for 30 seconds or so, rinse for 30 or so, back to backwash for another 30, etc. In my mind I considered it "pulsing" the sand. Then when I was done I would run the rinse cycle for 2 to 3 minutes. Worked really well doing this especially those times when I needed to drain rainwater. Not sure if this procedure is what did the trick or if it was a combination of finally getting the pool "right" plus the addition of skimmer socks but I havn't had this problem any more since late in the season last year.

 

[duraleigh]

Usually rinsing takes <30 seconds total.

All pools are different, but my pool requires a rinse cycle of at least a minute.

If I rinse for less than that, I get a greenish cloud back into the pool.

 

[Knucklehead]

Thanks for the advice. I don't see a "Rinse" option for my Sand Filter. I'll have to dig through my documentation, But I'm not sure there is one.

 

[BoDarville]

Knucklehead:

If you do not have a rinse setting, you can give the filter a deep cleaning using the following procedure:

• 1. Make sure pump is off and will not come on until you have finished all of the following steps.
  2. Unscrew the filter cap at the top of the filter housing (usually this is black with 2-4 spokes on it that allow you to better grip the cap for removal and re-attachment)
  3. Place a garden hose inside the filter and turn the water on until a gentle flow is coming from the hose.
  4. Let the water overflow out of the top of the filter. You will likely see a fair amount of gunk. Gently agitate the sand a bit. Continue until water runs clear.
  5. Replace filter cap, then run pump and check for leaks.

 

[Knucklehead]

I see that the rinse option definitely is not available because we have a Slide valve instead of a Multiport valve. Maybe that is an upgrade we need to make. The Multiport backwash procedure includes a 1 minute rinse step. There is a step in Slide valve backwash process in the manual that has an air release valve that needs to be open until water flows steadily from the valve. I don't see a filter cap except where the pressure meter and air release valve are. I'll remove them and rinse from there.

 

[MassNerd]

Yeah, I saw the 30-1 min in the instructions, but my PB said rinse until the water runs clear. I was relieved to hear this because when the pump is at high speed, an alarming amount of water is drained from the pool. Could be as much as 1 inch per minute. Meanwhile it takes me almost 2 hours from my well to fill that much.

So I don't get a cloud after rinsing for only 15-30 seconds. It is after the pump has been off for a while and hasn't been backwashed in a few days. Still filtering dirt out of my pool from the install. Is that normal?