Please review my results / odd FC issue

[Shelbrain]

Hello TFP!

I am a new pool owner with the water being filled just over 30 days. I have a 12x27 PebbleTec pool with an Aquarite 900 SWG, SwimClear CS200 cartridge filter. According to an online calculator it is roughly 11,542.5 gallons. The builder added salt and handed over the pool to me. He also added a bottle of Jacks' Magic Magenta Stuff while he was in control of the pool. Builder initially set SWG at 60% which produced consistently high FC levels.

Here are today's test results from my TF-100 test kit. The FC has been extremely high over the last two weeks, so much so that I reduce the SWG to 30% last week and turned it off for the last two days in an effort to reduce the FC levels. On the initial Chlorine test, I am getting a bright orange reading and a Google search indicates it is over a testable amount. I was expecting the FC to drop however it has not done so. I took a water sample to both Leslie's and Pinch-A-Penny and they said my FC was 7.0 and "high"-is this because that as high as their test reads? It took 43 drops this morning on FC test for it to go clear so that is where I came up with 21.5 FC. I have been adding 20oz of muriatic acid every 2-3 days to keep pH in check as recommended in the Pool Math app.

FC 21.5
pH 7.5
TA 90
CH 250
CYA 40
Salt 4200
CSI -0.54
Temp 60 degrees F

The builder originally set the Aquarite at 60%

 

[Jimrahbe]

Shel,

Trust your reading.. shut the SWCG off.. This time a year, it will take a week or more to come down to a usable range..

You can't test your pH when the FC is higher than 10 ppm...

In the summer you will want your CYA to be 70 or 80, since you are using a SWCG.

Thanks,

Jim R.

 

[Shelbrain]

Jim,
Thanks for responding! I am so glad to hear I am not going crazy! Should I not be adding any acid then since I cant test the pH. Are you saying the results wont be valid because of the extremely high FC? The builder did leave me with a half opened bag of stablizer to make adjustments to the CYA later down the road if needed.

Also since I have your attention, the builder set the Hayward Omni TriStar VS950 Omni pump to run at 2001RPM (medium speed) from 8:00am-6:00pm (10 hours) a day? Is this too much? Would perhaps lowering the runtime help accelerate the FC drop?

What do you think about the Magenta stuff. I am a big fan of keeping the basics so I wasnt sure what the forum thinks about this stuff.

 

[Jimrahbe]

Shel,

The Magenta stuff was most likely to keep down the plaster dust.. I suspect you will want to clean your filter once things settle down..

Running the pump will not increase or decrease the rate at which your FC will get used up.. In this case the sun is your friend, as it will consume the FC..

I would not screw with the CYA until the spring... We keep higher CYA in SWCG pools to help keep the FC from burning off so quickly. Not much of an issue this time a year, but in the middle of the summer, it will mean you won't have to run your SWCG so hard to keep up with the FC demand.

For reference, I run my VS pump at 1200 RPM, but I also run 24/7. It is not at all required, but I like to make a little chlorine all the time.

The two main reasons to run your pump are to generate chlorine and to keep the surface of your water clear (skimmed)..

In the summer, most pools use between 2 and 4 ppm of chlorine.. Your SWCG, set at 100%, will produce 3 ppm of chlorine in about 5 hours... Or, you can set your cell to 20% and it will produce 3 ppm of chlorine in about 24 hours... By adjust your SWCG's output and your pump's run time, you can set a run time that works best for you...

I would not worry about the pH being a little until the FC drops below 10 ppm.

Thanks,

Jim R.

 

[Shelbrain]

Thanks for the followup response. I will monitor the FC until it comes down.

 

[aplanedrvr]

Hey Shel,
I’m in Central Florida with a water temp of 63*. I ended up shutting the SWG off and adjust the FC with bleach. As you have found out, it takes a long time for the FC to drop off and I was in your situation where my SWG was producing too much chlorine, even at 20%.

 

[Shelbrain]

Hey Shel,
I’m in Central Florida with a water temp of 63*. I ended up shutting the SWG off and adjust the FC with bleach. As you have found out, it takes a long time for the FC to drop off and I was in your situation where my SWG was producing too much chlorine, even at 20%.

Yeah, I am in Hernando County and I never thought it would get cold enough to shut off SWG but I thank you for the reassurances. It's been overcast so that is another reason why it may be coming down slower.

 

[Shelbrain]

01/01/2019 Update; Happy New Year!

These are today's results. I am a bit more confident in my test results today using the TF-100 kit with the exception of the CYA. The Aquarite SWG has been off since I posted here previously but based on the results I would like opinions on turning it back on at a low percentage, such as 10% to ensure it maintains the FC level.

FC: 4.0
pH: 7.8
TA: 70
CH: 150
CYA: 30 (the dot doesnt really go away for me)
Salt: 3200 (the previous 4200 result must have been a misread)
CSI: -0.45
Temp: 69 degrees F

PoolMath Android app is recommending to add 12oz of 31.45% Baume muriatic acid to lower pH. I last added 19oz. of muriatic acid 5 days according to my PoolMath logs.

Pool is looking great! Thanks in advance.

 

[Jimrahbe]

Shel,

Based upon your readings it makes sense to turn the cell back on. I'd start at 10% and see what happens.

If the dot does not go away in the CYA test, it normally means you have close to zero CYA. Not as much of an issue this time a year as it is in the middle of the summer.

A pH of 7.8 is just fine... I would add MA if it reaches 8.0..

Thanks,

Jim R.

 

[Texas Splash]

I wouldn't add any more acid at this time. As you can see from PoolMath, your CSI is already a bit low (potential to be corrosive). The colder water has a lot to do with that. The new plaster needs the CSI to be closer to neutral (0), so just keep an eye on that. As for the FC, you're fine at the moment. Your call if you wish to use the SWG periodically to maintain that FC. Bleach or SWG is fine as the colder water "should" help to keep the FC from dropping quite as fast as it would in the summer. Simply monitor it with your TF-100.

There's Jim! Good morning.

 

[Shelbrain]

Thanks to you both for your help

 

[Jimrahbe]

Pat,

I'll give you it is morning anyway.. A little nippy up here this morning..


Shel,

Ok... one guy says to turn your cell on, and the other guy says keep it off. How can both answers be right???

Your FC is fine where it is (4 ppm) See this chart.. Pool School - Chlorine / CYA Chart

I personally like to run my FC on the high side of the range.. As an example... with a CYA of 30 the range is 4 - 6, I like to run at 6.. This allows me to slack off and not test so often.

I use the non-saltwater table anytime the CYA is below the recommended SWCG level..

Thanks,

Jim R.

 

[Shelbrain]

Pat,

I'll give you it is morning anyway.. [emoji14] A little nippy up here this morning..


Shel,

Ok... one guy says to turn your cell on, and the other guy says keep it off. How can both answers be right???

Your FC is fine where it is (4 ppm) See this chart.. Pool School - Chlorine / CYA Chart

I personally like to run my FC on the high side of the range.. As an example... with a CYA of 30 the range is 4 - 6, I like to run at 6.. This allows me to slack off and not test so often.

I use the non-saltwater table anytime the CYA is below the recommended SWCG level..

Thanks,

Jim R.

Thanks!

 

[Shelbrain]

I ended up turning my SWG back on at 10% and it has maintained a 4.0 FC with 0.0 or 0.5 CC since my last post. I am at the point now where I would like to tackle some of the other results. I have been adding 12oz. of 31.45 Baume muriatic acid roughly every 3-4 days to keep my pH in check.

Today's results:
FC 4.0
pH 7.8
TA 70
CH 150
CYA 30?
Salt 2400
CSi -0.46
Water Temp 64 degrees F

I was thinking about adding some Calcium Chloride to the pool to increase the Calcium Hardness (CH) result. PoolMath suggests a range of 350-450 whereas the TF-100 testkit suggests 250-400 for masonry pools. I was going to purchase it on Amazon and add in small amounts at a time until I reach my desired target. What would be a good target since there is a difference in the two suggestions.

Also, has anyone had experience with the PuriTech Calcium Chloride product on Amazon. It seems like the best price/pound over the name brand products I could find.

 

[Shelbrain]

Bump

 

[ajw22]

Get your CH to at least 250. That amount protects your plaster and grout from leaching out CH. After that use CH to dial in your CSI. Optimum CSI is between 0 and -0.3.

Use PoolMath to model your CSI at winter and summer water temperatures.

Remember that you can only remove CH with water draining. Do better to target low then high.

 

[Shelbrain]

Get your CH to at least 250. That amount protects your plaster and grout from leaching out CH. After that use CH to dial in your CSI. Optimum CSI is between 0 and -0.3.

Use PoolMath to model your CSI at winter and summer water temperatures.

Remember that you can only remove CH with water draining. Do better to target low then high.

Thanks! I'll shoot for 250 then. From reading online, my plan is to fill a 5 gallon bucket 3/4 full with pool water while it is sitting on the pool steps to dissipate some heat, add 1lb of calcium chloride and stir to dissolve. Once dissolved, pour around the perimeter of pool while the pump is running. I plan to repeat this process every couple days until I reach 250