Newbie salt (dumb) question on cell % and run time

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cbink

cbink

0
Feb 4, 2013
609
Houston, Tx
Hey!

My pool build got finished up about 6 weeks ago and we added salt about 10 days ago. Since then I've been struggling to keep my FC < 8.
I note there is general advice about tweaking the cell and the pump time but is there a good rule of thumb about where to start?
My cell is currently running at 20% (it got started at 50% and I've been dropping it to try and control the FC) and still keeps the FC at about 8, CYA at 80. Salt is currently at between 2,800 and 3,000.
Should I set my salt cell to 50% and then reduce the pump times to keep the FC at the 4-5 mark? I don't feel I should drop the cell to less than 20% as clearly I have got my timings slightly wrong at the moment... I'm going off the assumption that it's best to change one thing at a time rather than changing the pump timings and the salt cell percentage. I started by dropping the cell down as I assumed it would only take a small change (I was wrong!).

The cell is a Hayward T-40 running through a prologic8. The pool is about 26,000 gallons so I would expect to have some leeway on the cell, just not as much as I'm seeing.

I'll run a full set of tests tonight as we've had a lot of rain today so some of my values may change.

Appreciate any advice on a good starting point.
 
linen said:
I would reduce pump time first, since that would likely be most efficient. Have you looked at this pool school article?: http://www.troublefreepool.com/pool-school/pump_run_time

As temperatures get cooler, you will need less swg on time.
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Thank you.
Yes, I have read the article but struggled to find a starting point for SWG, only 4 hours to circulate the chlorine on a standard 'chlorine' pool.

I guess I'll set the salt cell to 50% and drop the pump run time until I'm approximately where I need to be (so long as I'm > 4 hours pump run time). From there I should be able to tweak the SWCG +- to keep the FC in range and then adjust pump run times seasonally. Is that the best approach?
 
Seems like it to me. I wouldn't shy away from upping the swg percentage and reducing the pump run time in the winter, although what do I know...soon my pool will be a block of ice. How long have you been running the swg lately?
 
You can go less than 4 hours, often I have read that 2 hours of run time in the winter is enough ... as long as the SWG is keeping up.

It really does not matter the combination of run time and % setting ... the wear on the SWG will be the same for the same amount of FC produced.
 
cbink,
I too am pretty new to this pool thing, but I recently replaced my chlorinator and so read around them a bit. I have no doubt others know way more than me, but here goes:

Trying doing a brief look for a Hayward T-40 in their range of chlorinators, I could only find a Hayward Tcell-15 with would handle a pool up to 40,000 gallons. Is that what you have?

Assuming that you do, again looking at the range, the next model down provides for pools up to 25,000 gallons, so it appears that you are just beyond that one. I think it's reasonable to assume that you aren't going to be running the chlorinator at anywhere near full tilt.

For my old Zodiac at least, the model numbers for their chlorinators referred to grams of chlorine per hour that can be produced, (according to literature, my LM2-24 produced up to 24 grams per hour... when it was working!), so following the same logic, a T15 may produce 15g per hour.
The next model down in Hayward's line is the T-9, and that is good for a 25k Gallon pool. Mathematically, you would only need 4% more than that ( a T-9.36!) to cope with a 26k pool, but with a T-15 you could have 60% more!

If these assumptions on chlorine production are correct (I accept that they may not be) your T-15 chlorinator cell running at 63% is equivalent to the "T-9.36" you need, which should be as much as you would ever need for your pool.

The conclusion:
I would think that it's highly likely that you can run with the percentage WAY down, especially as it cools and even less chlorine is required.

edited for typos
 
To be clear, we recommend sizing the SWG between 1.5-3 times larger than your pool size. So for a 26k pool, a 40k cell is the MINIMUM size we would recommend. The point being that you do not have to run the cell as much and it should last longer.
 
No doubt sage advice from jblizzle (I knew people knew more than me!)

So that being the case, it would make sense that cbink could be running the SWG for a much shorter time/much lower percentage, as that would be the whole point of the recommendation.

I am interested in this, as I have just installed a new chlorinator myself (oversized), but haven't set it up yet. Waiting on test kit to arrive, then SLAM, then I'll tune the SWG.
 
linen said:
Seems like it to me. I wouldn't shy away from upping the swg percentage and reducing the pump run time in the winter, although what do I know...soon my pool will be a block of ice. How long have you been running the swg lately?
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The pump now runs on high for 4 hours, then on low for 8 hours. Previously it was set to run 10 hours on high and 9 on low (new pool thus higher run times although I can probably drop it further).
 
Your current run time is still pretty long, especially for cooler months. I would try 1 hour on high (just for skimming) and 3 on low and see if all looks good (assuming your swg can produce enough chlorine with that amount of time).
 

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linen said:
Your current run time is still pretty long, especially for cooler months. I would try 1 hour on high (just for skimming) and 3 on low and see if all looks good (assuming your swg can produce enough chlorine with that amount of time).
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It's down to 2 on high, 4 on low at 20% and seems to be doing fine. I left it slightly longer to help skimming as I do get a bit of debris off palm trees into the pool.
I'll keep an eye on the FC but right now it appears to stay at a pretty steady 4.
 
I am still running mine 8 hours a day on 20 % at low speed. I have a variable speed pump. My FC has been between 4 - 6. My water temperature here in Texas is still around 70 degrees every day so I am remaining quite vigilant on the water chemistry as I am sure garbage will have no problem still growing in at in that temperature.

During the Heat of Summer I was running it 10 - 11 hours a day at 60 = 70 % to keep my FC where I wanted it.
 
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