Fourth SLAM this Summer due to algae. Am I doing this right?

[chem geek]

IF you are regularly having the chlorine get to zero, it sounds like you don't have the SWG on-time set high enough or that your weather is varying and you have it set to handle semi-cloudy days but not sunny ones. You should probably run your SWG longer and with a higher FC target until you get the hang of things in terms of what SWG on-time is needed to maintain the minimum FC. So target higher until you figure out how not to go below the minimum. Note that if you do not run the pump at all at night, that you need to target higher than 4 ppm FC at the end of the day so that there is still 4 ppm FC the next morning when the pump comes on. Basically, you should test your FC in the morning before the pump comes on since that should be the lowest FC level of the day if you are only running the pump during the day.

Your Hayward Goldline T-CELL-15 Turbo SWG outputs 1.47 pounds of chlorine per day which in 35,000 gallons is 5 ppm FC per day or [EDIT] 0.21 [END-EDIT] ppm FC per hour. That [EDIT] is woefully inadequate for your size of pool [END-EDIT]. What is your pump currently on and what is your SWG % on-time setting?

 

[Dagobah]

Well if your seeing hints of green you need to SLAM it. I know this is getting old but.....
If your getting algae again your not keeping your FC in range for the CYA level or you didn't complete the other SLAM.
How long does your pump run ? For your current CYA level for a SWG your FC range should be 4-5 and never below 3. You may want to bump that CYA level up to 70-80 when you get the SLAM over with.
You also will need to lower your PH into the low 7's for the SLAM. Your shock level is 24.

I've been running the pool for 16 hours a day this summer, and the cell is set to 90%. The last slam, I did not adjust the pH before beginning. Not sure if that would have affected it.

I am 100% positive I passed the overnight test the last go around. Not sure what I can do different this time.

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Have you been brushing the pool? It is recommended during a SLAM to brush daily, and at least weekly when the SLAM is over.

Brushed daily during the SLAM and weekly afterwards.

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I know you have a SWCG, but are you testing at least FC and pH every day?

I checked it every day or so afterwards and check it a few times a week at most. Usually weekly. My schedule is such that daily checks forever aren't feasible.

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IF you are regularly having the chlorine get to zero, it sounds like you don't have the SWG on-time set high enough or that your weather is varying and you have it set to handle semi-cloudy days but not sunny ones. You should probably run your SWG longer and with a higher FC target until you get the hang of things in terms of what SWG on-time is needed to maintain the minimum FC. So target higher until you figure out how not to go below the minimum. Note that if you do not run the pump at all at night, that you need to target higher than 4 ppm FC at the end of the day so that there is still 4 ppm FC the next morning when the pump comes on. Basically, you should test your FC in the morning before the pump comes on since that should be the lowest FC level of the day if you are only running the pump during the day.

Your Hayward Goldline T-CELL-15 Turbo SWG outputs 1.47 pounds of chlorine per day which in 35,000 gallons is 5 ppm FC per day or 0.63 ppm FC per hour. That should normally be enough during the day for your pool if you have the pump running when the sun is out and hitting the pool, say 12-14 hours, and your % on-time is at least 25%, but given your experience it should probably be set higher. What is your pump currently on and what is your SWG % on-time setting?

16 hours a day this summer (during daylight hours) set to 90%. I increased it from 12-16 hours a few months ago and increased the % after these issues started.

 

[chem geek]

I made a mistake in my post and corrected it. The 1.47 pounds of chlorine per day which in 35,000 gallons is indeed 5 ppm FC per day, but that is only 0.21 ppm FC per hour (a day has 24 hours, not 8 that I originally used) which is barely adequate in full sun during the day. 16 hours at 90% would be 3 ppm FC per day, BUT during peak noontime sun your chlorine loss might be higher than 0.2 ppm FC per hour so your FC may drop and algae may start to grow. That means needing to boost up to a higher FC before that happens. Your earlier 12 hours with <90% was likely not adequate to maintain a proper FC level.

Do you have a full set of water chemistry numbers you can post? Maybe your pH, TA and/or CH are high resulting in calcium carbonate scaling in the salt cell that is reducing its output. Do you see white flakes coming out of the returns on occasion when the cell reverses polarity? Have you checked/cleaned your cell recently? When you had your CYA lower in the past, that was probably not adequate. With your barely adequate SWG cell you need 70-80 ppm CYA in order to protect the chlorine enough from sunlight. Did you ever add the 50 ppm Borates you were considering that could help control pH from rising and also control calcium carbonate scaling in the SWG cell?

 

[tim5055]

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I checked it every day or so afterwards and check it a few times a week at most. Usually weekly. My schedule is such that daily checks forever aren't feasible.
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You are going to need to find a way to check it a little more often. Once a week give the algae several days head start then the FC gets too low.

 

[Dagobah]

I made a mistake in my post and corrected it. The 1.47 pounds of chlorine per day which in 35,000 gallons is indeed 5 ppm FC per day, but that is only 0.21 ppm FC per hour (a day has 24 hours, not 8 that I originally used) which is barely adequate in full sun during the day. 16 hours at 90% would be 3 ppm FC per day, BUT during peak noontime sun your chlorine loss might be higher than 0.2 ppm FC per hour so your FC may drop and algae may start to grow. That means needing to boost up to a higher FC before that happens. Your earlier 12 hours with <90% was likely not adequate to maintain a proper FC level.

Do you have a full set of water chemistry numbers you can post? Maybe your pH, TA and/or CH are high resulting in calcium carbonate scaling in the salt cell that is reducing its output. Do you see white flakes coming out of the returns on occasion when the cell reverses polarity? Have you checked/cleaned your cell recently? When you had your CYA lower in the past, that was probably not adequate. With your barely adequate SWG cell you need 70-80 ppm CYA in order to protect the chlorine enough from sunlight. Did you ever add the 50 ppm Borates you were considering that could help control pH from rising and also control calcium carbonate scaling in the SWG cell?

Where would I get a full set of chemistry numbers? I cleaned the cell a few months ago after I had it tested. Have not seen flakes coming out, although I do see a bit of what I believe is sand in the pool every week when brushing. I do have some sort of white calcium in a few spots in the pool and a decent bit in the spa. Those have been there for years.

Have not added borates.

 

[pwrstrk]

Where would I get a full set of chemistry numbers? I cleaned the cell a few months ago after I had it tested. Have not seen flakes coming out, although I do see a bit of what I believe is sand in the pool every week when brushing. I do have some sort of white calcium in a few spots in the pool and a decent bit in the spa. Those have been there for years.

Have not added borates.

Richard means a full set of test results. ?

 

[Dagobah]

You are going to need to find a way to check it a little more often. Once a week give the algae several days head start then the FC gets too low.

I was checking it a few times a week the first week after the completed overnight test. However, everything I've ever been lead to believe was only once a week checking was necessary. If I were to hire any pool maintenance company, wouldn't they only be coming out once a week?

 

[Dagobah]

Also, your stats suggest the T-CELL-15 should not be used in a pool my size. Howard rates these for up to 40k gal. As far as I know, that's the biggest T-CELL they make. What other options do I have, and why have I had 4+ previous years of success with it? (Pool came with the house with this setup).

 

[tim5055]

I was checking it a few times a week the first week after the completed overnight test. However, everything I've ever been lead to believe was only once a week checking was necessary. If I were to hire any pool maintenance company, wouldn't they only be coming out once a week?

You should check daily - maybe every other day so you can catch teh chlorine as it is going down if your SWCG has issues. Sure they would only test once a week but would throw a floater in the pool with tabs and send your CYA through the roof.

Also, your stats suggest the T-CELL-15 should not be used in a pool my size. Howard rates these for up to 40k gal. As far as I know, that's the biggest T-CELL they make. What other options do I have, and why have I had 4+ previous years of success with it? (Pool came with the house with this setup).

I can only guess due to my limited knowledge of SWCG, but it may be getting old and deeding replacement soon. In past years it may have had more "life in it".

Options include a new larger SWCG or automated dosing with liquid chlorine.

 

[Dagobah]

You should check daily - maybe every other day so you can catch teh chlorine as it is going down if your SWCG has issues. Sure they would only test once a week but would throw a floater in the pool with tabs and send your CYA through the roof.

I can only guess due to my limited knowledge of SWCG, but it may be getting old and deeding replacement soon. In past years it may have had more "life in it".

Options include a new larger SWCG or automated dosing with liquid chlorine.

Keep in mind I replaced the swg about 12 months ago.


Sent from my iPhone using Tapatalk

 

[chem geek]

We always recommend to get an SWG that is oversized for the pool because the manufacturers woefully undersize them and their "ratings" are really on the edge. As you have found, it is workable, but it's iffy. For your size of pool you'd normally either have two such cells or a larger model which they do make such as Saline C 6.0, but it depends on price. The T-CELL-15 retails for $645 but can be obtained on Amazon for $410 while the Saline C 6.0 is $3900 so clearly two T-CELL-15 would be more economical and they would likely last about twice as long as one cell. Anyway, you've got one and can probably make it work.

So once you get things under control you've got some choices. You can either be diligent and set the pump runtime and the SWG on-time to make sure it's able to keep up (and that also means having the CYA closer to 80 ppm and never letting the FC get below 4 ppm) or you can use separate products to control algae growth. Such products are not necessary if chlorine levels are maintained, but you can look at them as insurance.

 

[Dagobah]

We always recommend to get an SWG that is oversized for the pool because the manufacturers woefully undersize them and their "ratings" are really on the edge. As you have found, it is workable, but it's iffy. For your size of pool you'd normally either have two such cells or a larger model which they do make such as Saline C 6.0, but it depends on price. The T-CELL-15 retails for $645 but can be obtained on Amazon for $410 while the Saline C 6.0 is $3900 so clearly two T-CELL-15 would be more economical and they would likely last about twice as long as one cell. Anyway, you've got one and can probably make it work.

So once you get things under control you've got some choices. You can either be diligent and set the pump runtime and the SWG on-time to make sure it's able to keep up (and that also means having the CYA closer to 80 ppm and never letting the FC get below 4 ppm) or you can use separate products to control algae growth. Such products are not necessary if chlorine levels are maintained, but you can look at them as insurance.

Ok, hadn't thought of running multiple cells. Would I have to also install an additional Aquarite controller? I believe it only has a plug for a single cell.

On the algae products, the local pool store had me try Phosfree. Any thoughts on that product?

 

[tim5055]

On the algae products, the local pool store had me try Phosfree. Any thoughts on that product?

Skip the PhosFree and go for a quat based algecide like PolyQuat 60

PhosFree isn't really an algecide, it is a phosphate remover.

 

[chem geek]

I believe they just wire the cells via separate power supplies to run in parallel -- both on or both off -- and you still just adjust the % on-time for them overall. However, for powering the second cell, it very likely requires a second power supply and I don't think they separate out the power supply from the controller.

PhosFree is one way to inhibit algae (by removing an essential algae nutrient) though there are other phosphate removers that are much less expensive (when accounting for their concentration) such as Orenda PR10,000 for $45 per quart that removes up to 10,000 ppb phosphate in 10,000 gallons compared to 1 quart of PhosFree removing only 600 ppb per 10,000 gallons for $24.15 for 3 liters so $134 per 10,000 ppb so much more expensive than the Orenda product.

However, use of this product (usually added once with possible later additions if fill water has phosphates or you get blown-in fertilizer) or of Polyquat 60 algaecide (added weekly) needs to be seen as insurance-only since they are not necessary if the FC level is maintained consistently above the minimum needed for the CYA level. The only time a phosphate remover or a calcium scale inhibitor would be necessary would be if both phosphates and calcium were very high resulting in calcium phosphate scaling in the salt cell. That does not sound like your situation. Another option is to use 50 ppm Borates which also have mild algaecidal properties, pH buffering capability, and would prevent scaling in the SWG cell, but for your size pool that can also get expensive -- 50 ppm would require 83-1/2 pounds of boric acid which from Duda Diesel would be around $110. For comparison, GLB Algimycin 600 which is a Polyquat 60 algaecide is $16.74 per quart and for 35,000 gallons the weekly maintenance dose would be 10-1/2 fluid ounces in 35,000 gallons so $5.50 per week. You can see why preventing algae growth from chlorine alone is far more economical, but does require diligence.

 

[Dagobah]

I believe they just wire the cells via separate power supplies to run in parallel -- both on or both off -- and you still just adjust the % on-time for them overall. However, for powering the second cell, it very likely requires a second power supply and I don't think they separate out the power supply from the controller.

PhosFree is one way to inhibit algae (by removing an essential algae nutrient) though there are other phosphate removers that are much less expensive (when accounting for their concentration) such as Orenda PR10,000 for $45 per quart that removes up to 10,000 ppb phosphate in 10,000 gallons compared to 1 quart of PhosFree removing only 600 ppb per 10,000 gallons for $24.15 for 3 liters so $134 per 10,000 ppb so much more expensive than the Orenda product.

However, use of this product (usually added once with possible later additions if fill water has phosphates or you get blown-in fertilizer) or of Polyquat 60 algaecide (added weekly) needs to be seen as insurance-only since they are not necessary if the FC level is maintained consistently above the minimum needed for the CYA level. The only time a phosphate remover or a calcium scale inhibitor would be necessary would be if both phosphates and calcium were very high resulting in calcium phosphate scaling in the salt cell. That does not sound like your situation. Another option is to use 50 ppm Borates which also have mild algaecidal properties, pH buffering capability, and would prevent scaling in the SWG cell, but for your size pool that can also get expensive -- 50 ppm would require 83-1/2 pounds of boric acid which from Duda Diesel would be around $110. For comparison, GLB Algimycin 600 which is a Polyquat 60 algaecide is $16.74 per quart and for 35,000 gallons the weekly maintenance dose would be 10-1/2 fluid ounces in 35,000 gallons so $5.50 per week. You can see why preventing algae growth from chlorine alone is far more economical, but does require diligence.

Thanks again, great info here. Do people ever switch back from a SWG to a traditional chlorine setup? I've loved the water feel with the SWG, but this summer has been a beast as this thread demonstrates. Just wondering what all my options might be.

 

[kcindc]

I am currently a manual jug tosser, I add bleach daily. I am looking to switch to a SWG soon because hauling a cart full of bleach weekly and adding bleach daily is a pain.

Others have already given you the best options:
1. Stick with your T-CELL-15 and supplement with daily manual bleach additions (low up front costs)
2. Get another T-CELL-15 and run two SWGs (probably most convenient and long-term economical choice)
3. Replace your unit with a larger SWG from a different manufacturer (high up front cost)
4. Switch to adding bleach daily (either manually or using a pumping system).

 

[chem geek]

Well, with your size of pool you'd be lugging a lot of weight of chlorinating liquid and that's harder to find and not as economical in Texas as elsewhere. 2 ppm FC per day in 35,000 gallons would be somewhat over 1/2 gallon of 12.5% chlorinating liquid every day or nearly 4 gallons per week.

An SWG is usually the way to go for automation and convenience. It's just that they sized the SWG on the edge and didn't make a unit sized (in their weak terms) for 60,000 or 80,000 which would have been better for your pool. You're probably better off managing what you have, either with running longer or getting another SWG cell or using a supplement. Did the pool store give you a specific phosphate level for your pool? That would give you an idea if that's a feasible approach if you wanted insurance.

 

[Dagobah]

Well, with your size of pool you'd be lugging a lot of weight of chlorinating liquid and that's harder to find and not as economical in Texas as elsewhere. 2 ppm FC per day in 35,000 gallons would be somewhat over 1/2 gallon of 12.5% chlorinating liquid every day or nearly 4 gallons per week.

An SWG is usually the way to go for automation and convenience. It's just that they sized the SWG on the edge and didn't make a unit sized (in their weak terms) for 60,000 or 80,000 which would have been better for your pool. You're probably better off managing what you have, either with running longer or getting another SWG cell or using a supplement. Did the pool store give you a specific phosphate level for your pool? That would give you an idea if that's a feasible approach if you wanted insurance.

This is the only pool I've owned, but had assumed traditional pools just used chlorine pucks. Hearing this, it does sound like a SWG is the better route.

I've done some searching on the forum about adding a second cell, all I'm seeing is this thread. One reader suggests a second aquarite would be needed. Also sounds like the cells would need to be plumbed in succession. Neither are things I was hoping for.

For now I'm continuing the SLAM, in the mean time I'll be seeing what it would take/cost to add a second cell.

 

[chem geek]

Yes, Trichlor tabs would be far less weight at around 4-1/2 pounds of tabs per week (around 9-10 tabs depending on their weight). However, at 2 ppm FC per day that would be 36 ppm CYA per month. Keeping the CYA in check requires significant dilution of the water from backwashing a sand filter and summer rain overflow and a short swim season with additional dilution over the winter. One can get lucky with tabs if their pool is poor in algae nutrients (in which case less tabs can sometimes be used), but for many pools algae forms when the CYA level climbs and the FC level is not proportionately raised and yours has already proven that it can grow algae.

 

[Tepelus]

Upgrade your pool with a UV lamp. You will never have to SLAM again as long as the UV lamp is working.