Use of main drain to control flow

Mattsway

Bronze Supporter
Apr 10, 2017
30
Sussex UK
#1
Hi, I'm running my pump 24/7 during my first SLAM and all is moving in the right direction.

The problem is, I have a small suction leak and am spending ages bleeding the air, especially in the morning.

I have slowed the leak by only using the main drain to the pump, so the skimmer valve is closed because that's where most of the air was leaking in.

Can I further slow the leak by partially closing the main drain? Would doing that make a difference, or would the reduced pressure reduce the efficiency of the bleeding?
My pump is oversized by design to give the fast turnover that might be needed in a hydrotherapy pool used by my disabled son. I was thinking that I could reduce the flow rate now there is a zero bather load. The usual pressure at the filter is 16psi.

The suction pipework is inaccessible to me and the builders aren't available to fix it for a while, which is no problem with usual use of the pump of max 3hours a day, needing only 1/2 hour bleeding.
 

Mattsway

Bronze Supporter
Apr 10, 2017
30
Sussex UK
#2
Related to the above, do I need to have the pump running 24/7 during the SLAM given that the water is clear? Once the chlorine is mixed in after a full turnover, does it need constant circulation to react with the organisms in the water? Just a newbie's brain ticking over...Possibly completely wrong.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
31,327
Sebring, Florida
#3
Keep your pump running until you complete the SLAM.

Is the water level in the pool high enough to keep the skimmer(s) from sucking air? Why do you think it is the underground pipe from the skimmers causing the air intake?......it rarely is the cause.
 

pooldv

Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
24,993
DFW, TX
#4
It is generally best not to try to choke the flow down on the suction side of the pump. There is risk of cavitation and pump damage
 

Mattsway

Bronze Supporter
Apr 10, 2017
30
Sussex UK
#5
Keep your pump running until you complete the SLAM.

Is the water level in the pool high enough to keep the skimmer(s) from sucking air? Why do you think it is the underground pipe from the skimmers causing the air intake?......it rarely is the cause.
Please see my last post for the suspected cause;

Air in pump when heating on?

Water level is half way up the skimmer. I have lubed all o rings and run water over the pump lid and suction pipework without success. I also tried cling film and smoke to check for air getting sucked in. Shutting off the skimmer line slowed the rate at which the pump sucked air. The suction pipework at the skimmer end is under plywood, the top of which is covered by the vinyl covering the pool.

- - - Updated - - -

It is generally best not to try to choke the flow down on the suction side of the pump. There is risk of cavitation and pump damage
Thanks for this. I'll leave it fully open.