Newbie SWCG and High Alkalinity also Pump Run time ?

[kimbro]

Hello! Long time lurker, 1st time poster. Please be gentle

18,000 Above Ground SWCG in full sun from about 10AM until 7/8pm
FC 3
PH7.2
CYA 100
Alkalinity 180
Salt 3000ppm (Aqua Trol)

Decided to install a SWCG to my above ground 18,000 gallon pool. *Loving* it so far All of my readings are pretty much on target except for my Alkalinity which was off the charts. (Alkalinity has always been very high and in past years (doing BBB) I was told by my local pool guy not to worry about it too much as everything else was fine. :/) I'm reading this is a NO-NO for salt water. I researched and added a gallon of muriatic acid and it did lower it to 180 now. So I should continue adding acid until it gets to 80? And then assuming I will need to aerate to raise what I assume will be a lower PH.
Next question please excuse my ignorance, is it a basic rule of thumb to have SWG making chlorine during day every day? I have mine set at 40% (started at 50) but honestly am having a hard time even knowing what that means. The manual that came with is not the most helpful...I've tried understanding reading through posts but ...suddenly everything sounds like the teacher from Charlie Brown wah wuh wah wuh wah wuh wuhhhh.
What I think I gather is to set it at say 50%, take a FC reading in the evening and then if it is fine I lower it a bit and the following day take a FC reading in the evening and go from there. The lowest % output that keeps it at around 3 is where I set it?
Thank you in advance for your help

 

[linen]

Welcome to tfp, kimbro

First, the cya result you listed is very high. How did you get it? If you believe that number, then I would do a partial drain/refill to lower it down to 70-80 ppm cya.

Do you have a number for CH?

I was told by my local pool guy not to worry about it too much as everything else was fine.

If you are not having scaling issues in your cell, then I would agree with his statement.

You can take a couple of approaches here:
1. Let TA take care of itself but watch ph closely (assuming you do not have scale problems on your cell). When the ph goes up to 7.8 (and it will), lower it back down to 7.2 with Muriatic Acid (MA).
2. Take an active approach and aerate the water to speed up the ph rise...and again when ph reaches 7.8 add Muriatic Acid to lower it back down to 7.2. See: http://www.troublefreepool.com/pool-school/lowering total alkalinity

What I think I gather is to set it at say 50%, take a FC reading in the evening and then if it is fine I lower it a bit and the following day take a FC reading in the evening and go from there. The lowest % output that keeps it at around 3 is where I set it?

Well at 100 ppm cya, your minimum FC should be 5 ppm at anytime. You rational on how to get there is sound though. Most likely you are running the pump longer than you need to (most people do) so having a shorter run time with the swg at a higher percent might be a better choice (or might not). See: http://www.troublefreepool.com/pool-school/pump_run_time

 

[duraleigh]

Welcome to the forum. :lol:

I would adjust the CYA down to about 70-80 ppm and then keep your FC right around 4 ppm.

If you choose to keep CYA at 100, your FC should be about 6 ppm and it will require about 40 ppm (yikes) if you ever need to shock the pool.

Unless you feel like your pH is continually rising and you are using too much muriatic acid to control it, I would leave the TA alone.

 

[kimbro]

Thank you everyone! I should have also mentioned I just installed my SWG last weekend so this is all very new to me... I wouldn't think I would have a problem with scaling from the alkalinity being high as it has only been running a week? But if this would be a potential problem, I think I will add 1 more gallon of acid and see where that gets me down to.
I got my results (CYA etc) from the pool strips that came w/ my SWG (I will be getting the TF100). We live kind of in the "boonies" so I don't get into town as often as I would like, but I will take a sample of my water into the pool guy hopefully in the next week or so and he will be able to tell my my Calcium Hardness and get an exact # on CYA. What exactly will the hardness affect/harm?
I do know that "pool guy" had me keep CYA on the higher side (80) (haven't added any stabilizer since 2011 though) due to the fact that my pool is literally in the sun from sun up to sun down and I was getting a lot of chlorine loss due to burn out. How much water would I need to drain out? I do lower the water level each year at seasons end to below skimmer and refill each spring with fresh water. Appreciate your help! Thanks

 

[linen]

But if this would be a potential problem, I think I will add 1 more gallon of acid and see where that gets me down to.

If you still at 7.2, I would not add any acid now. Wait until your ph is up at 7.8, then lower it to 7.2. Make sure you use the poolcalculator.com to get the correct dosage.

I got my results (CYA etc) from the pool strips that came w/ my SWG (I will be getting the TF100)

Wait to adjust cya (drain/refill) until you get results from the tf-100. Test strips are useless for cya.

Here are the tfp recommendations for swg water balance: http://www.troublefreepool.com/pool-school/water_balance_saltwater_generator