New VS pump...with old pool

Searstj

Member
Apr 8, 2021
13
Indiana
Pool Size
18000
Surface
Vinyl
Chlorine
Liquid Chlorine
Hello all,
Was in the middle of our slam process when our single speed pump crapped out. I went ahead and decided to get a Hayward max flow variable speed 1.65 HP pump, hoping to cash in on some of the electrical savings moving forward. Since my pool is far from new and has the original 1.5 inch plumbing (probably around 40feet of head - guessing), I’m trying to figure out how to optimally run this VS pump without stressing my plumping/filter/Pump.

According to the Hayward manual “when installing the max flow VS pump care should be taken to ensure proper pipe and equipment sizing to handle the maximum flow required. It is recommended to set the maximum speed in order to not exceed the maximum flow rate. The maximum flow rate for pipe size 1 1/2 inches is 45 GPM“.
Without buying a flow meter to install on my plumbing, how the heck do I know this? I’m also in the middle of slamming my very green pool, so not sure if I run the pump at 3450 RPM until blue or if this is going to put way too much pressure on my system.

Once the pool is blue I’m not too concerned with GPM as most threads on here advocate turnover rates for pools aren’t really that accurate to maintain blue water, and I can more or less just set pump at a low RPM to make sure I’m getting adequate circulation.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
41,454
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
No reason to be concerned about the exact flow rate. You run the pump at the speed needed to perform the function at hand. So for normal skimming and filtering, a low rpm is all that is necessary. Find the rpm that provides skimming and set it at that for the base rate.
 

Searstj

Member
Apr 8, 2021
13
Indiana
Pool Size
18000
Surface
Vinyl
Chlorine
Liquid Chlorine
No reason to be concerned about the exact flow rate. You run the pump at the speed needed to perform the function at hand. So for normal skimming and filtering, a low rpm is all that is necessary. Find the rpm that provides skimming and set it at that for the base rate.
So for my current task(slam) am I ok to run at 3450? This is really where a lot of my concern is stemming from, as I don’t want to kill my equipment trying to push ~100gpm through 1.5 plumbing, but at the same time I don’t want to be slamming for the next 4 weeks because I dropped the rpm so low.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
41,454
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
No need to run at that level. I would suggest trying 1200 rpm and see if that skims the surface.

Brushing and vacuuming the solids during a SLAM to the filter is more important than pump speed.

What is your filter pressure?
 

Searstj

Member
Apr 8, 2021
13
Indiana
Pool Size
18000
Surface
Vinyl
Chlorine
Liquid Chlorine
No need to run at that level. I would suggest trying 1200 rpm and see if that skims the surface.

Brushing and vacuuming the solids during a SLAM to the filter is more important than pump speed.

What is your filter pressure?
Clean filter pressure at full rpm is about 4-5 psi. If I lower my pump speed to under 3000 my filter doesnt even give a reading on the gauge.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
41,454
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
With a sand filter, it will take time to clear the pool. The DE will help. Brushing and vacuuming will help. But turnover is not a factor, as you are dumping the 'clean' water back into the 'dirty' water. So you just need to get the solids to the filter, and the filter in a position to trap those solids.
 
Thread Status
Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.