Replacement SWG

[NLandas]

Whoa....I've never seen a SWCG that dirty but I bet you it works now.......The folks in here (TFP) are awesome....Anyway, I also almost bought a new cell if it wasn't for the little button that says service that I have to reset....My sidekick (my 17 year old) forgot to do it after he cleaned the cell....He was doing good there for a while.....The cell is alive and kicking.....and I'm about to do a final test in abit......Goodluck ShallowWater.....I have the same SWCG as yours.....keep 'em clean!!!!!

 

[mknauss]

Remember, properly managed pool water chemistry should keep a SWCG free from scale build up.
Recommended Levels

 

[chlorinatorpro]

That's great news! Hopefully you will get a few more months or a year from the cell. Anything is gravy right now. You may have to eventually turn up the duty cycle to 75-80 (or more) if you think chlorine output is lacking at 25%.

One other thing. From your pictures it looks like the plastic housing (holding the plates) is warped in some spots. Don't know if that's from sticking an object between the plates to dig out some calcium or if you had a water flow issue at one time that allowed the plates to be charged without sufficient water flow. Or it could just be the angle of the picture?

 

[ShallowWater]

Remember, properly managed pool water chemistry should keep a SWCG free from scale build up.
Recommended Levels

My levels are in those ranges. Being a salt water chlorinated pool I struggle with keeping pH down. Yesterday's test is below. I like the FC a bit higher but given that I haven't been generating enough with the SWG, it is a bit low using Liquid Chlorine right now. That hopefully will come up over the next few days.

Results from poollogger.com

FC: 3
CC: 0
PH: 8.2
TA: 80
CH: 250
CYA: 70
Temp: 82
Salt: 3200
CSI: 0.25

Quick question on the Recommended Levels link. The first page shows a maximum CyA of 60ppm for SWG but the FC/CyA Chart it shows up to 80ppm and has 60ppm indicated as not recommended. I usually try to keep mine at 70ppm to 80ppm with FC at 7ppm.

 

[ShallowWater]

Whoa....I've never seen a SWCG that dirty but I bet you it works now.......The folks in here (TFP) are awesome....Anyway, I also almost bought a new cell if it wasn't for the little button that says service that I have to reset....My sidekick (my 17 year old) forgot to do it after he cleaned the cell....He was doing good there for a while.....The cell is alive and kicking.....and I'm about to do a final test in abit......Goodluck ShallowWater.....I have the same SWCG as yours.....keep 'em clean!!!!!

My bad.. I haven't cleaned the dang thing since summer 2019. I've been lackadaisical to say the least! Up until the heat came on around here the FC levels seemed to be doing okay but with the current high UV Index I'm sure it was burning up FC faster than my SWG could make it even with a CyA of 70.

 

[ShallowWater]

That's great news! Hopefully you will get a few more months or a year from the cell. Anything is gravy right now. You may have to eventually turn up the duty cycle to 75-80 (or more) if you think chlorine output is lacking at 25%.

One other thing. From your pictures it looks like the plastic housing (holding the plates) is warped in some spots. Don't know if that's from sticking an object between the plates to dig out some calcium or if you had a water flow issue at one time that allowed the plates to be charged without sufficient water flow. Or it could just be the angle of the picture?

I'm running at 35% now and will monitor it.

The plates were bent from cleaning I believe but what is a recommended flow rate? Here's the pump curve for my pump. I run it at 1400rpm 7 hours at day, 2200rpm 5 hours a day and 3450rmp 2 hours a day. The flow rate is constant up to about 10GPM for the 1400rpm curve and 15GPM for the 2200rpm curve and at least 20GPM at 3450rpm. I'm not sure what my head is but I could get out my hydraulics book and calculate it; even then I'd have to make some wild assumptions about pipe runs, not knowing exactly how it is plumbed as I didn't own the home when the pool was built.

 

[mknauss]

Quick question on the Recommended Levels link. The first page shows a maximum CyA of 60ppm for SWG but the FC/CyA Chart it shows up to 80ppm and has 60ppm indicated as not recommended. I usually try to keep mine at 70ppm to 80ppm with FC at 7ppm.

All depends on climate, geographical location, etc. For the majority of pools in the forum with a SWCG, a CYA of 70-80 is appropriate.
Interesting on your test data. Your low CH should lend you to having no issues with scale in your SWCG. I have never cleaned scale out of my SWCG in 6 years. And my CH level is never below 300 ppm, and right now I am heading above 700 ppm. You just need to control your pH more.

 

[ShallowWater]

All depends on climate, geographical location, etc. For the majority of pools in the forum with a SWCG, a CYA of 70-80 is appropriate.
Interesting on your test data. Your low CH should lend you to having no issues with scale in your SWCG. I have never cleaned scale out of my SWCG in 6 years. And my CH level is never below 300 ppm, and right now I am heading above 700 ppm. You just need to control your pH more.

I think I probably need to replace my reagents for hardness as my readings have dropped from a consistent 350ppm to now be more in the 225 to 250 range. I'll check with the water district on their numbers because in CA you have to report these things and I'll also check what I get at the tap.

 

[ShallowWater]

Overnight my FC went from 7 to 6 but it could be user error as CC is still 0 and the water is clear. I bumped my SWCG to 70% too, BTW, so I expected a rise overnight as the pump goes from midnight to 4am at 1400 RPM then to 2200 RPM at 4am when I am up and can enjoy the cascade of water out of the raised spa into the pool below with the colored lights.. but maybe that isn't enough flow to produce now given the possible degraded state of the SWCG. What is the required flow rate, @chlorinatorpro ?

I replaced my reagents with un-expired reagent out of the Fridge and it is still 250ppm on the CH. The tap read 150ppm but I'm going to call the water district and see what they know about it although they may report as TDS and not as CH.

 

[ShallowWater]

The local water district's water quality report indicates the following for CH so my readings are accurate on the tap it would seem. Do I need to add calcium carbonate?


First number is average, second it range.

 

[Rancho Cost-a-Lotta]

Your CH is good. Calcium stays in the water with evaporation. Each time you top-off, you add more calcium. Read up on calcium saturation index (CSI) and maintain your CSI level between 0.0 and -.30 to mitigate scaling. Adjusting pH and TA are the easiest way to remain in range.

Calcium Saturation Index (CSI)

How is CSI calculated? Very simple – use our PoolMath tool. To ensure long plaster life and save money, click here to learn more.

www.troublefreepool.com

 

[ShallowWater]

I thought CSI should be from +0.30 to -0.30?

 

[mknauss]

I thought CSI should be from +0.30 to -0.30?

Correct, without a SWCG. With a SWCG, best to keep between -0.3 and 0 to reduce scaling in your SWCG.

 

[ShallowWater]

Correct, without a SWCG. With a SWCG, best to keep between -0.3 and 0 to reduce scaling in your SWCG.

I'm wondering if a low CSI, below -0.30 will cause problems with plaster flaking or desolving?
Does a high pH drive the CSI down if all other items are held constant?

 

[mknauss]

A CSI under -0.3 is heading towards aggressive in nature and long term damage to plaster.

High pH raises CSI.

 

[ShallowWater]

A CSI under -0.3 is heading towards aggressive in nature and long term damage to plaster.

High pH raises CSI.

I just figured that out and this is why my cell is getting buildup on it. I struggle to keep pH below 8.2. This is weird though in that I do have some plaster flaking off even though my pH is higher than I'd like it to be and CH is in the 250 range.

Now back to that SWCG.. What flow rate is recommended to generate adequate FC? I posted the pump curve above and it seems lately that the FC production is lower than it used to be. This is why I started this whole thread..

 

[mknauss]

Flowrate needs to be high enough to close the flow switch for the SWCG. After that, flowrate does not matter for chlorine generation.

 

[NLandas]

Overnight my FC went from 7 to 6 but it could be user error as CC is still 0 and the water is clear. I bumped my SWCG to 70% too, BTW, so I expected a rise overnight as the pump goes from midnight to 4am at 1400 RPM then to 2200 RPM at 4am when I am up and can enjoy the cascade of water out of the raised spa into the pool below with the colored lights.. but maybe that isn't enough flow to produce now given the possible degraded state of the SWCG. What is the required flow rate, @chlorinatorpro ?

I replaced my reagents with un-expired reagent out of the Fridge and it is still 250ppm on the CH. The tap read 150ppm but I'm going to call the water district and see what they know about it although they may report as TDS and not as CH.

Sooner or later you'll find the sweet spot!!!! Here in Phoenix, AZ (2 miles away from heck), we're having our wonderful run (again) of 113-116 degree weather...I keep my Chlorine output @ 60% and FC so far has been between 7-10. I even tested it this week @ 5 PM and FC was @ 8......I did have a period where my son cleaned the cell but forgot to reset so it wasn't producing any and I thought cell was dead.....Whew!!!! dodged that one.....You got some real good folks here man......Now I'm saving for one of my lights which is just as expensive as the cell :-(.

 

[ShallowWater]

I had a sweet spot at 25% for years but I might have screwed the pooch by not cleaning my cell on time this year. I'm trying to re-calibrate knowing the end is probably nigh on my SWCG.

 

[ShallowWater]

So I have some great news!

Although I did not get the chance to check my FC last night, this morning it was at 10.0 and CC was 0.0 as it has been all along. pH was a bit on the low side at 7.5 bringing my CSI down below -0.3 but I suspect that will rise by itself as it always does so I'm not going to take action yet but I do have some Soda Ash just in case. I will continue to monitor FC and may drop the SWCG down from 70% to 50% if it holds but not yet because we're about to hit a long string of +100 days with several expected to by north of 110 so with temps like that I'm best to leave it be..