Pump timing

[kitamiman]

I would really appreciate some advice re pump timing on an infinity edge pool with a trough. Last year (I am down south so my pool season is the winter) I had an outbreak of black algae and I sure as heck don't want it back.

OK - two Intelliflo VS pumps, one circulating the pool water from floor drains in the main pool via filter and SWG to returns in the main pool and the other ('edge pump') bringing water from the floor drains in the trough back to dedicated returns in the main pool via separate filter. Currently I run the main pump at 1200 rpm and the edge pump at 1500 rpm. (Both pumps run at higher rpm for 1 min each time they kick in). Electricity is expensive so I am open to all advice regarding time/rpm.

My fill water has high TA (300); running the edge pump and circulating water over the edge (65') leads to high rates of evaporation and a rapid rise in PH, requiring more fill water at TA 300 and endless acid. I therefore want to minimize use of edge pump, but I am now really nervous about leaving water uncirculated in the trough for too long. How long is it safe for the trough water to sit without being recirculated? (I am aiming for 4.5 to 5 ppm chlorine.) Trough holds about 1500 gallons.

Last year I basically ran the pool pump for about 12 h on /12 h off (off overnight) and the edge pump for about three 1-hour runs staggered through the day - and I ended up in trouble. I am thinking this year I should spread circulation times on both pumps round the 24-h clock. I am thinking I'll go with about three 6-hour runs with three 2-hour intervals on the main pump (?), although I would quite like to reduce this to three 5-hour runs with three 3-hour intervals if that was safe. I have no idea what my best plan of action is with the trough...

All help gratefully received.

 

[Bama Rambler]

There are people who run a lot less time than you ran and don't have problems. You should be able to get by with running the main pump 12 hours at 1000 rpm and running the edge pump about an hour a day. You may be able to get away with running the main pump less time than that.

I'd say we start with a set of test results and how you go them.
pH
FC
CC
TA
CH
CYA

Another important thing to do is run the FC & CC test just after the main pump kicks on a few times, or even just before it kicks on. That way you'll know what the FC is at the worst possible time. It may be dipping too low between runs. You should also check different areas to see if you have a circulation issue.

 

[JasonLion]

Extended periods of very high PH caused by the combination of high TA and the aeration from the negative edge, or very low PH caused by over correcting high PH with too much acid, could cause problems. The combination of high TA fill water and a negative edge makes an automatic acid feed system of one kind or another very attractive.

 

[kitamiman]

Thanks Jason.

I have an Intellichem and a peristaltic acid pump waiting to go in, so hopefully that will help.

 

[kitamiman]

OK - test results this morning 2 hours after start up:

FC = 4.5
CC = 0.25 or less (v. feint pink)
pH = 7.8
TA = 150
CYA = 25
CH = 225
Salt = 2800
Temp = 69

Will add 2 qts acid, 70 oz stabilizer, and 120 lbs salt and try to test just before start up tomorrow.

Pool was refilled 2 weeks ago and there is a sizeable leak somewhere. Salt has dropped from 3400 to 2800 in 2 weeks so water loss of 1" plus a day is not just evaporation. Since we know about it we are testing salt and CYA every couple of weeks and adding salt/stabilizer as needed. Leak has so far eluded all efforts to find it. Unfortunately it may be that the shell is porous in places - gunite was done badly. Shell was waterproofed before tiling using crystal-based technology (Crystal X) , but that relies on a reaction with the cement so if the lousy contractor snuck in some rebound with low cement content then the system is gonna fail. When it comes to the pool construction, I wish my cake were dough!

 

[Bama Rambler]

Your CYA is low but if you're losing 1" per day that's understandable.

Your TA is high but with fill water at 300 and having to replace 1" per day it's just gonna take acid and time to get it down.

Hopefully you can find the leak and have it repaired soon and then I think a lot of your problems will go away or lessen a lot.