Hello, and a question about CYA with a SWG

Brett S

Active member
Mar 15, 2019
44
Orlando
OK, so this is my first post here, so I’ll start by saying hello and giving you a bit of background. And so you can understand how we have wound up in the situation we are now in I will fully admit that I am the type of person who will buy something first and do my research second. I realize this is backwards and often winds up costing me more time and money in the end, yet here I am. But hey, they say that admitting you have a problem is the first step, right? ;)

So my pool journey started last year when my parents were visiting and bought my kids a little 6x10x2 inflatable pool. I would set it up and fill it and they would play in it for a weekend and then I’d take it down a couple of days later so the water wouldn’t get stagnant and the grass under the pool wouldn’t die. The kids loved playing in the pool, but I hated dragging it out and setting it up and then emptying it and putting it away a few days later. After dealing with this for much of the summer one fateful day last august my kids were begging me to set up the pool again and I thought that there must be a better way. I looked around and discovered that since it was near the end of the season Target had a 15x48 intex pool on clearance for $150. I figured that this pool was big enough that even I could use it, plus came with a filter so it could be set up permenantly. So I ran to target and got the pool and some chlorox pool test strips and some of the chlorox shock and chlorine tablets.

I set up the pool and filled it... and then realized that it was 6” off level. Like I said, I tend to act first and research second. So I spent a bit of time on google and discovered that this was a bad thing and then drained the pool and spent much of a day leveling the ground where it was going to go. I refilled the pool and the good news is that it’s less than 1/2 an inch off now:)

Even though it wasn’t set up until halfway through august I live in Florida, so we still had a couple of months to use it before it got too cold out. I used the chlorox test strips and the chlorox app to tell me what chlorox chemicals to put in. I struggled keeping up with the water chemistry a bit during that time, primarily because I didn’t really even understand what I was doing... I was just letting the app tell me if things were good or bad or what chemicals I needed to add. I was also doing my testing with cheap test strips of questionable accuracy. But I made it through the end of the season without ever letting algae overtake the pool or having any other really bad things happen. Since it doesn’t freeze here in Florida I decided to just leave the pump running all winter and keep the pool chlorinated rather than shutting it down and winterizing it. Unfortunately I wasn’t quite as diligent about adding chlorine as I should have and I wound up with very green water.

As it is starting to get warmer again here in Florida I decided that it was time to get the pool back in shape and I decided that I needed to do a bit more research and try to do better this year. I discovered a number of things... First, I needed to get a real test kit instead of relying on the test strips, so I ordered the K-2006 kit.

Second, I had seriously overdosed on CYA... right from the the beginning, because I didn’t realize that it needed a long time to dissolve. The chlorox app told me to add stabilizer to the new water, which I did, then I tested 4 or 6 hours later and it was still showing very low, so I added another full dose of CYA. Then to make things worse, the chlorox products I was using for chlorine and shock were Trichlor and Dichlor, so that just kept adding to my CYA. According to my new Taylor test kit it was somewhere north of 100ppm. I realized that I needed a better way to chlorinate the pool.

Third, I realized that the tiny pump and cartridge filter that came with the pool was very undersized and I needed a better filter.

I liked the chlorine tablets because I didn’t need to worry about chlorinating the pool every day. I could just add some tablets every week or so and be done with it, so I really didn’t want to switch to liquid chlorine that I would need to measure and add more frequently... that seemed like taking a step backwards. As I looked at chlorinization options I realized that a SWG was probably the best option for me and since I wanted a bigger filter too I immediately set about researching SWG and filter options... OK, so if you know anything about me by now you know that’s not true. Instead I immediately went out and bought the Intex ECO-20110 salt water system. This has a pump, a 16 inch sand filter, the intex SWG in one unit and it moves 2150GPH through the system. It’s definitely oversized for my little 4440 gallon pool, but I didn’t want to wind up with too small of a filter and I figured that if I upgraded to a larger pool in a few years that I could keep using the same filter.

I also realized that I needed to do something about my very high CYA levels, so I drained and replaced more than half of the water in the pool. This brought it down to 48ppm according to my Taylor test kit.

So as I’ve been continuing to research water chemistry I discovered the TFP website and read many of the pool school articles. I also found the recommended water parameters for SWGs. After the partial drain and refill my water isn’t bad, but alkalinity was a bit higher than ideal, so I’ve been slowly bringing down with muriatic acid while aerating the water to keep the pH from dropping too low. When I tested this morning my parameters were as follows:

6.4ppm free chlorine
<.2ppm combined chlorine
7.4 pH
105ppm total alkalinity
180ppm calcium hardness
48ppm cya.

I added another dose of muriatic acid after I took those readings and that should bring my alkalinity down to 80 or 85ppm, but I’ll test again in a few hours.

So, after all that, here is my question... the recommended parameters for SWG pools suggest keeping CYA at 70 or 80ppm (on a side note, I really wish I had read that *before* I drained and refilled my pool to bring my cya down to 48). However, the all in one Intex filter/SWG doesn’t have any way to schedule the pump to run without the SWG... the SWG is always at 100% and runs whenever the pump is running.

Since this SWG system is oversized for my small pool I’m a bit concerned that the SWG will be limiting my pump runtime... in other words, if I run the pump long enough to keep the water circulated and the pool clean then my chlorine levels will be too high. If I lower the runtime to keep my cholorine levels where they should be then the filter won’t run long enough to keep the pool clean.

So with that in mind I’m thinking it might make sense to keep my CYA levels lower than the 70-80ppm that’s recommended to allow some of the chlorine to burn off which would allow me to run the system longer to give the filter more time to clean the pool. However, in my research I couldn’t really find any explaination of why it is recommended to keep the CYA levels higher on a pool with a SWG than a pool without one. Is there a problem with keeping my CYA levels a bit lower, other than a need to run the SWG longer (which in my case may be a benefit)?

And if you’ve made it through this entire post, thanks for reading and any thoughts you have here:)
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Welcome! :wave: Woo, that was a lengthy intro. :) Ha Say about that question ....
However, the all in one Intex filter/SWG doesn’t have any way to schedule the pump to run without the SWG... the SWG is always at 100% and runs whenever the pump is running.
Are you sure about that? According to the manual, there appears to be some time settings for operating hours.
ECO 20110 Manual
 

Brett S

Active member
Mar 15, 2019
44
Orlando
Welcome! :wave: Woo, that was a lengthy intro. :) Ha Say about that question ....

Are you sure about that? According to the manual, there appears to be some time settings for operating hours.
ECO 20110 Manual
Yes, you can set operating hours, but unfortunately since it’s an all in one system there is just one timer. If it’s on the pump, filter, and SWG are on, and if it’s off the pump, filter and SWG are off. There is no way to run the pump and filter without the SWG. (At least not automatically with the timer... you can manually start the pump without the SWG, but I’m definitely not going to be doing that every day)
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Oh, I see this now:
7. Running the pump alone without the Saltwater System:
To run the pump alone without the Saltwater System function, press and
hold both (
) and (

the LED display shows "FP". The pump is now operating alone. To stop the

pump, manually turn the switch OFF. NOTE: The pump cannot be operated
alone under an automatic timer mode.
But then you are basically doing things manually to re-set the timer. Hummm. Maybe another ECO owner will have a thought.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
11,446
Bedford, TX
Brett,

Welcome to TFP.. A great place to learn all about how saltwater pools really work. :shark:

Your plan will work just fine...

We recommend a higher CYA to allow the SWCG to not work so hard generating chlorine and because you are adding a little chlorine over a longer period time.. Unlike when adding a lot of liquid chlorine all at once.

Another option, and the one I would use, would be to add a time clock to control just the SWCG.. Basically, having the pump controlled by one time clock that feeds a second time clock. For example... You could have your pump run from 7 am until 7 pm and then schedule your SWCG to get power from 10 am until 1 pm. This would allow you to precisely adjust the amount chlorine your SWCG could make..

Thanks,

Jim R.
 

Brett S

Active member
Mar 15, 2019
44
Orlando
Another option, and the one I would use, would be to add a time clock to control just the SWCG.. Basically, having the pump controlled by one time clock that feeds a second time clock. For example... You could have your pump run from 7 am until 7 pm and then schedule your SWCG to get power from 10 am until 1 pm. This would allow you to precisely adjust the amount chlorine your SWCG could make..
Thanks for the reply, but unfortunately even this won’t work as the system I have really is an all in one unit and it just has a single power cord for the pump and SWG. I may be able to open it up and add a second power cord for the pump if I really need to, but I’d rather avoid doing that if possible.

I’ve literally only had it connected and running for 24 hours now and I’ve only just started the SWG this morning as I was waiting to ensure that the salt has fully dissolved, so this might not even wind up being a problem for me. But for the time being I’ll go ahead and leave my CYA where it is and see how it goes and how long I need to run the system to maintain my chlorine level. If it seems like I get enough runtime on the pump and filter then maybe I’ll bump the CYA level up a bit, but if not I’ll just leave it as is.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
4,461
Northern NJ
When I tested this morning my parameters were as follows:

6.4ppm free chlorine
<.2ppm combined chlorine
7.4 pH
105ppm total alkalinity
180ppm calcium hardness
48ppm cya.

I added another dose of muriatic acid after I took those readings and that should bring my alkalinity down to 80 or 85ppm, but I’ll test again in a few hours.
With a pH of 7.4 you should not be adding MA to lower your pH further. Focus on keeping your pH in the 7's. Your TA is fine unless you have a problem with your pH. Don't focus on your TA alone and try and drive it to a number.

How do you get a reading of 48ppm for CYA when the test tube has lines in the 10's? The scale is logarithmic and you cannot eyeball values in between the lines. Fill the tube until you cannot see the dot and then call the CYA the next line down so you are rounding up.

You only need a few hours of pump runtime to keep your water clean. Find out what pump/SWG runtime keeps your FC to the target for your CYA level as shown in FC/CYA chart. I think you will be okay with that pump runtime.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Aside from your plan to leave the CYA low, (which one would assume should result in FC getting used quicker), I wonlder about the thought of simply not maintaining the proper amount of salt? Less salt means less than optimum FC output? Is one any better than the other I wonder in your case with that all-n-one system?
 

Brett S

Active member
Mar 15, 2019
44
Orlando
With a pH of 7.4 you should not be adding MA to lower your pH further. Focus on keeping your pH in the 7's. Your TA is fine unless you have a problem with your pH. Don't focus on your TA alone and try and drive it to a number.
I was adding MA to lower the TA and aerating to keep the pH from dropping too low. I was doing so based on the suggested parameters for pools with SWG listed in the pool school articles here... Trouble Free Pool which says:

Adjust your Total Alkalinity to 60-80 ppm. (This is IMPORTANT!)
So to some extent I am just chasing numbers here as I don’t really understand the logic behind it, but I do trust the advice here and it says that it’s important in capital letters:).

How do you get a reading of 48ppm for CYA when the test tube has lines in the 10's? The scale is logarithmic and you cannot eyeball values in between the lines. Fill the tube until you cannot see the dot and then call the CYA the next line down so you are rounding up.
I didn’t realize that I couldn’t just eyeball in between values. In my case it was most of the way to 50, so I called it 48, but I guess I should just call it 50ppm.

Thanks for your reply:)
 

Brett S

Active member
Mar 15, 2019
44
Orlando
Aside from your plan to leave the CYA low, (which one would assume should result in FC getting used quicker), I wonlder about the thought of simply not maintaining the proper amount of salt? Less salt means less than optimum FC output? Is one any better than the other I wonder in your case with that all-n-one system?
That’s an interesting thought too. From the manual I know that it will shut off if the salt is too low, so I probably can’t lower it significantally, but running it on the low side of normal might be enough to lower the chlorine output a bit as well. Although TBH I don’t really even know what the salt level is right now. The manual suggested adding 110lbs of salt based on my pool size which was supposed to get it to 3000ppm, which I did, but then I realized that I don’t have a test kit to measure salt level. I ordered the Taylor kit and it’s supposed to arrive this afternoon, so I should know within a few hours exactly what my salt level is.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
4,461
Northern NJ
I was adding MA to lower the TA and aerating to keep the pH from dropping too low. I was doing so based on the suggested parameters for pools with SWG listed in the pool school articles here... Trouble Free Pool which says:

So to some extent I am just chasing numbers here as I don’t really understand the logic behind it, but I do trust the advice here and it says that it’s important in capital letters:).
The problem with generic articles is it is difficult to make it apply to all situations. You have an AGP with a SWG which is not the common configuration. When you have a SWG in a plaster pool it is more important to keep TA low to keep pH from rising rapidly.

In your situation you can ignore your TA unless you find that your pH constantly is drifting above 8 every few days. Even then, if you just lower your pH regularly then over time you will lower your TA.

FC and pH are the two primary tests to focus on. If those get out of wack bad things can happen.

CYA and TA by themselves don't matter. Nothing bad happens if they are high or low. Except that CYA affects the FC level you can maintain; and TA affects the rate that your pH may increase. So if you have a problem with FC or pH then the first thing you look at is CYA or TA.
 

jtpipkin

Well-known member
Oct 2, 2016
84
albany, ga
That’s an interesting thought too. From the manual I know that it will shut off if the salt is too low, so I probably can’t lower it significantally, but running it on the low side of normal might be enough to lower the chlorine output a bit as well. Although TBH I don’t really even know what the salt level is right now. The manual suggested adding 110lbs of salt based on my pool size which was supposed to get it to 3000ppm, which I did, but then I realized that I don’t have a test kit to measure salt level. I ordered the Taylor kit and it’s supposed to arrive this afternoon, so I should know within a few hours exactly what my salt level is.
you sound like my brother from another mother ;) - i did the same in the beginning - i had a destination and i wanted to be there yesterday... it got a little squirrely chasing the numbers at first here too. wasn't sure which was more important and didn't ask. in the end, and only a short period of time, they all settled and the advice was sound. i test now for fun. very little work to do once you get it all balanced. only advice from a fellow newbie, slow down. follow the rules, don't get in a hurry and add slowly, test, repeat if necessary. good luck!
 
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Brett S

Active member
Mar 15, 2019
44
Orlando
Well, just to follow up on this, I decided to return the Intex all in one pump/sand filter/SWG and purchase a stand alone Intex pump/sand filter and stand alone Intex SWG. I’m still within my return period and it turns out that the two stand alone units together are only $5 more than I paid for the all in one.

As I’ve been playing with the system over the last few days I’ve discovered that for right now, at least, with the low temps and my solar cover on the pool I’m losing less than 1ppm of FC a day, so with the all in one system that means 1 hour of runtime for the SWG and the filter and I just don’t think that’s enough to keep the pool clean and well circulated. I’m sure that during the height of the summer I’ll need to generate more chlorine than that, but during the spring and fall when the chlorine demand is low I’m just not sure I’ll get enough filter run time with the all in one unit.

The stand alone units will have their own power cords and timers and I’ll be run the pump/filter for a reasonable amount of time and then just activate the SWG for an hour a day.

I also debated going with non Intex equipment since I’m returning the unit that I have, but frankly I’m spending just under $300 total for both the pump/filter and the SWG and I’m not sure there’s really anything else that can come close to that price. The Intex equipment also has the advantage of not needing any funky plumbing adapters to work with my Intex pool.
 

Brett S

Active member
Mar 15, 2019
44
Orlando
Well, to follow up on my follow up, unfortunately Intex thwarted my wonderful plan. I got the new pump/filter and new SWG and everything was great with the pump/filter. It had it’s own power cord, of course, as well as a physical switch so I could use a timer to turn it on and off. Unfortunately, I discovered that the new SWG has an electronic switch, so every time the power goes out it turns off and you need to press the button to turn it back on, so it can’t be used with an external timer.

Also unfortunately, the internal timer is pretty terrible. You configure the system to run for X hours a day and it immediately begins running as soon as you finish configuring it. It will run for X hours, then shut off and start again at the same time the next day. Obviously I could try to sync the SWG’s internal timer with my pump’s timer, but I imagine that over time they would drift and require resetting. And every time the power failed the SWG would need to manually be restarted (and manually restarted at a specific time, because it will start running as soon as you turn it on, then run again 24 hours after that). If the power failed while I was away for a few days then my pool wouldn’t be getting chlorine which would kind of defeat the whole purpose of having a SWG in the first place.

So I reconsidered my options and discovered that the 2017 model of the intex standalone SWG does have a physical power switch and can be used with an external timer. I was even able to find some new old stock of the 2017 model, but oddly it was nearly $100 more than the 2018 model with the electronic power switch. I couldn’t quite bring myself to spend $100 extra on an older model, so I decided to go back to the all in one unit, which luckily I hadn’t returned yet.

I went ahead and opened the unit up and added a second power cord for the pump. So now it has one cord coming out that runs the pump and one cord that runs the SWG. It had a physical power switch, which is still connected to the SWG portion, so I can leave that on and run both parts with timers. I’m using timers connected to my home automation system, so I can be sure that the SWG only runs when the pump is on, and I can also configure the SWG to run in shorter increments than 1 hour so I can fine tune the chlorine output if I need to.

I feel like intex made this a whole lot harder than it needed to be, or maybe I made it harder than it needed to be because I wanted more control than the horrible internal intex timers could provide, but in any case, I think I have something that’s going to work for me now at a reasonably inexpensive price.
 
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