Dust plumes from outlets on pump start

Nov 15, 2019
5
Johannesburg RSA
Hi. I am looking after a pool, which this website has helped with tremendously, but I'm occasionally experiencing an issue that I'd like to solve. I've noticed that sometimes, when switching on the pump in the morning, plumes of dusty water enter the pool from the filter's two water outlets. The colour is light milky brown. After a few seconds the water pumping in turns clear. This would typically happen when I switch it on after I'd cleaned out and replaced the weir baskets; however this sometimes happens even when the pump components have not been disturbed, say after being switched off for the night. The dirty water is not enough to make the entire pool murky but it does feel like it's just putting dust back into the pool that must then be re-filtered.

I live in South Africa where we've had a hot, dry spring so far, so I've been trying to backwash sparingly to save water. Normally I'd try to backwash for two minutes and then rinse for 1 minute every week or so. The dusty water sometimes happens even with a good backwash schedule. I believe the sand in the filter is pretty old but I'm not sure if this would have an effect, or whether to tell if it needs replacing. Chemical balances in the pool are all within acceptable limits, as far as I can tell.

I'd appreciate any insight into why this happens, whether it should/should not happen, and how to mitigate it. Thanks!
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
13,041
Evans, Georgia
Elvis, welcome :)

I take it you have a sand filter, so you really don't need to backwash it as often as you have been. You should have a pressure gauge on the filter and we recommend only backwashing when the pressure rises 25% over your baseline clean pressure. A *slightly* dirty filter actually helps capture other crud. Maintenance and Cleaning of Pool Filters - Trouble Free Pool

This is, of course, assuming your filter's innerds are all intact and the sand has not become channeled. Sometimes the laterals in the filter become cracked or damaged and allows schmutz to re-enter the pool. You can check for this by removing all the sand and *carefully* lifting the inner contraption and inspecting. Replacement bits and parts are available usually.

Do you have access to *pool* Diatomaceous Earth (aka "Pool DE filter aid")? Adding a bit of that (per our directions, please) can help you capture the smallest bits.

The dust only happens on start up, correct? Once the pump is up-and-running, it doesn't continue does it?

Maddie :flower:
 
Nov 15, 2019
5
Johannesburg RSA
Thanks for the response. To answer your questions: yes, it only happens sometimes when I start the pump for the day, and shortly after the dirty water clears up and runs clean.

As for your suggestions: unfortunately there is no identifiable pressure gauge in the pump system. In the absence of a pressure gauge, how often might a sand filter be backwashed? Are we looking at once in two weeks or once in six months? Further, would the symptoms I describe be consistent with damaged laterals? Finally, I doubt I've seen DE on the shelves, but I'll take a look next time.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
33,382
Sebring, Florida
You desperately need a pressure gauge to help you diagnose your problem. I suspect your issue is not backwashing correctly. Do you have a multi-port valve with a "rinse" position and, if so, are you rinsing? You need a gauge to properly operate a filtering system.
Are we looking at once in two weeks or once in six months?
It depends entirely on what your gauge tells you.
 

Etchase

Active member
May 22, 2019
33
Hawaii
I’ve had the same or similar issue. I had a small leak in the pump basket lid that was sealed when the pump was on, but allowed air to enter the system when the pump was off. The water in the filter is above the water level in the pool and the water would drain out of the filter when the pump was off. It appeared that this draining would somehow allow dirt captured by sand to migrate to the output side of the filter and result in a plume of dirt coming out of the returns when the pump started. I don’t know the mechanism that allowed migration to occurring and this is the only pool I have experienced it on. The solution was to fix the air leak, so no water drains back into the pool when the pump is off. This problem has recurred with different laterals and sand over 23 years. I have a Hayward 100 sand filter. Makes me very careful with the pump basket lid.
 

borjis

LifeTime Supporter
Aug 19, 2014
3,108
Pacific NW
I had that too, same as Etchase mentioned. Suction side like and when powering up, the guage would bounce around while
everything fills up. Once that was fixed, little bits of sand coming out the returns didn't happen ever again. In my case it was just a little sand coming out.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
33,382
Sebring, Florida
Again, I am fairly sure your issue is improper backwashing. 2 minutes on and one minute backwash is very likely not enough.

What does your water look like?

Get a pressure gauge installed.