Confusion as to CYA levels for SWG Pool

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realst8

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Aug 6, 2017
16
San Diego/CA
I just got a new K2006C test kit and this is what I found:

FC=1.5
CC=.5
TC=2
PH=8
TA=150
CH=200
CYA=85
Salt=2800 per InteliChlor

I realize I have some work to do but my first question is that the instructions for my pentair IC40 says my CYA should be 30-50 but pool school says 70-80. Which is right?
If the CYA only needs to go down to 80, its a big difference in amount of water to replace. I don't want to waste water and CYA if I don't have to. Pool is clear but also concerned with the lack of FC from the generator operating at 100% and I have always had problems getting it higher. I also found that Pentair recommends a salt level of 3600 ppm so I have to add more salt but want to correct CYA and TA first. Any answers appreciated and am I addressing the correct things first?
 
Hey there Realst8 -

Part of your problem is probably that your SWG is undersized for your pool based on our recommendations of sizing the SWG at 2-3x the size of the pool. Your device should put out 1.4# of chlorine per day. Right now I would suggest adding liquid chlorine (bleach) to the water to take you up to the desired FC level, and then seeing if your device will help maintain that.

We recommend a CYA level of 80, so you're really ok there.

Your TA isn't terribly odd considering your pH is standing at 8 now. WHen you use some muriatic acid to lower that pH (important to do soon) it will also help lower that TA. Here are the instructions --> Pool School - Lower Total Alkalinity

I always hesitate to suggest folks raise their salt level based on the device. I don't trust mechanicals over a true salt test kit. The Taylor K-1766 salt test drop kit is inexpensive and should provide you with results you can dose by. You appear under dosed at the moment if we can believe the SWG. When you add the salt make sure you turn the device off for a day or so to allow the salt to dissolve and mix in to the pool water before going thru the device.

Maddie :flower:
 
I added approx 150 oz of 14% muriatic acid spread around the pool and will add 96 oz of 10% chlorine to shoot for a FC of 4. After the Ph gets to 7.2, I will run the spa jets and spillway to aerate to raise the ph back up. How would I know if the SWG needs to be descaled? I believe I only need to order R-0630 and R-0718 reagents and can use the 10ML marking in the large tube to test the salt, correct?
 
On the salt test - I would assume so but would call TFTestkits.net to see.

In the future it is much safer to simply add your muriatic acid in one spot, at the return in your pool, with the pump running. You can pour from the acid jug or measure into a plastic measuring device with acid poured into it over the pool. Walking around the pool pouring in acid can easily splash and damage your clothes, coping, etc.

With a CYA of 85 (round to 90) you need to target 7 FC if your SWCG is keeping up. If not, use the non-SWCG levels in this chart Pool School - Chlorine / CYA Chart

It is not likely your IC40 has scale. Your CSI is not near the scaling tendency. The reverse polarity feature of the IC keeps the cell clean normally.

You do need to run your SWCG for up to 18 hours each day at 100% to maintain your FC. That will cover your normal daily loss of 2-4 ppm. You will be able to back that down soon as we get out of summer.

Take care.

- - - Updated - - -

You also asked about the CYA level. The TFP ranges are based on science and real world experience. The Pentair manual uses the standard pool industry numbers. They have been shown to be too low to protect your FC during the day such that you stay above the minimum FC.

Take care.
 
Did you use dry acid or muriatic acid to lower your pH? We prefer the use of muriatic acid (liquid).

The PoolMath app says that if you used 15% liquid MA you should reap a lower pH by 0.6 and a lower TA by 9.8. Did you get such results?

I would suggest you use the entire gallon of 10% LC as your pool is very large. 128 ounces will give you 3.3ppm FC.

I hesitate to suggest you do anything about your CH at this point because I know folks in your part of the country often deal with high calcium issues. At most you would want to take your CH to 300-350, knowing that with evaporation your CH will rise more as time goes on. You don't want too little as the water will leech calcium from the plaster, but you don't want too much either (risk of scale, etc). Pool School - Recommended Levels

Your SWG cell should be viewed for build up, but don't clean it unless it shows scale. Every time it gets cleaned with acid your lifespan of the cell decreases.

Maddie :flower:
 
Thank you for the responses. I used liquid acid from home depot. Do you know why Pentair recommends a CYA level of 30-50 for a SWG pool?
Since electricity is pricey her in CA, would it be better to look at a larger SWG like the IC60? I am running my pool 10 hrs as it is...
 
It would be best to get an IC60 next time. You also should have your VS pump at the lowest RPM needed to keep your flow switch shut on your current IC40. Many can get their RPM down to 1200 RPM, or close to 100W.

Pentair cannot change from the industry standard without being held responsible for someone finding a problem with their specific numbers. By using an industry standard, they are protected.
 
As Marty states above, the company uses a "one size fits all" approach to recommendations and its not practical. We have years and thousands of members experience that have contributed to our recommendations.

Yes to the larger cell. IC60 is for pools up to 60,000 gallons so is the right size for you.

Maddie :flower:
 
With the pump running, 30 minutes should be sufficient. If you like, push a brush around a bit to be sure it is fully mixed.
 

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When my SWCG is on I get a few bubbles at the return, but certainly not a cloud. Not sure what that is. Do you find flakes of calcium in your pool under the return?

You should have your SWCG set at 100% as you have struggled to supply enough chlorine to your pool. Even at a 100% setting, it only runs 265 seconds out of each 300 seconds.

Take care.
 
No flakes, actually the pool has never looked cleaner so I don't know what to make of it. Tomorrow I am going to clean the filter but it is showing only 10psi. I haven't cleaned it since a black mold episode a week or so ago that took a lot of scrubbing... I will also pull the lights and make sure no black mold exists. We mainly got it on our baja deck and the first step down from there. Again, thanks for all of the help. This all started due to a problem our manager was having at a hotel pool in the midwest. He is new to pools and kept running to the local store and they were more than happy to keep selling him stuff. I decided I wanted to know more so I could help him with that pool and mine also. I am going to send him the same test kit I bought and get him on the path to self sufficiency. They run that pool 24/7 because its commercial and they use a tablet feeder. If he gets away from the tablets, is it just a matter of adding x amount of bleach daily to maintain?
 
TFP is for private, residential pools. In some citys/countys; pools must be managed as per the health department standards. So the answer on the hotel pool is, it depends.

But if you can run the pool as TFP, yes, it could be as simple as you say. Is it indoor or outdoor? That makes a big difference. TFP standards are for outdoor pools.

- - - Updated - - -

If you maintain your FC based on the chart I linked to earlier, you should not get black mold or algae. Here is an article on that - Pool School - Black Algae

Be sure to follow the FC as shown on that chart. It is higher than what you probably have done in the past. But the best way to manage your pool.
 
I also live in San Diego and am concerned about the electricity to run the pump.

SDG&E bills me at 2 tiers:
#1 0-350 kWh = $.20
#2 350+ kWh = $.40.

Check out Solar PPA's. Lot's of companies have them. They are free and you will never get to the 2nd tier.

Saved me over $125/month.
 
YippeeSkippy said:
Did you use dry acid or muriatic acid to lower your pH? We prefer the use of muriatic acid (liquid).

The PoolMath app says that if you used 15% liquid MA you should reap a lower pH by 0.6 and a lower TA by 9.8. Did you get such results?

I would suggest you use the entire gallon of 10% LC as your pool is very large. 128 ounces will give you 3.3ppm FC.

I hesitate to suggest you do anything about your CH at this point because I know folks in your part of the country often deal with high calcium issues. At most you would want to take your CH to 300-350, knowing that with evaporation your CH will rise more as time goes on. You don't want too little as the water will leech calcium from the plaster, but you don't want too much either (risk of scale, etc). Pool School - Recommended Levels

Your SWG cell should be viewed for build up, but don't clean it unless it shows scale. Every time it gets cleaned with acid your lifespan of the cell decreases.

Maddie :flower:
Click to expand...

Just tested and got this:

FC=4
CC=.5
PH=7.6
TA=120

Am I happy at this point or do I need to increase FC to 7?
 
Back on this, todays readings:
FC=4.5
CC=.5
Ph=8 Keeps rising back to this
TA=130-140
CH=170
CYA=65
Salt measures 2750ppm on SWG

My questions:
Why does my ph keep rising to 8 after I lower it with muriatic acid?
Why is my CH down to 170 and do I need to push it up to 200 or higher?
Any other help as I seem to have trouble getting a handle on this.
 
PH is rising because the TA is high. PH will be more stable when pH is between 50 and 70. TA will drop as you add acid to lower pH. Or you can follow this process to lower it faster, Pool School - Lower Total Alkalinity.

Enter all your numbers into PoolMath and see what your CSI is. Keep CSI between -0.3 and 0. If the CSI is too low then raise the CH up to 250 or 300. You can use calcium chloride based ice melt. More here, Pool School - Recommended Pool Chemicals
 

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