SWG Cannot keep up

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M

marmo

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Nov 6, 2013
40
Northern New Jersey
I hope I can get some answers from the experts here. A little background on my pool. I had it installed last year, approx 30k gal, gunite with hydrazzo finish. I am using all Pentair equipment including an Intellichem which runs my IC40 with a Quad 100 taking care of the filtering. PH is kept in check with a Stenner dosing pump handling the Muratic acid.

I have read posts that the Intellichem using ORP to control the Intellichlor is not the best way to go because as the CYA reaches the upper levels for a Salt water poo (80-90) the ORP probe gets wacky. With that said I have kept my CYA 10 points above Pentair's recommended 50 to 60ppm to try and find a happy medium. But even at this level FC levels cannot be maintained and instead of being 650 ORP my reading will slowly drift to 300 range after a week and green algae will form on the walls unless I supplement with Bleach... Yesterday at Pentair's request I did a "bucket test" with the IC40 and yes it is producing chlorine.

My issue as I have stated in my title is my Chlorine is being burned off at such a fast rate that the IC40 Intellichlor cannot maintain appropriate FC levels and basically runs at 100% the entire filter cycle per day, 12 hrs. I find myself having to put bleach in at a non shock levels to keep the FC at 2-3 levels. Now I am not shocking it, this is just to maintain my FC levels. After much reading here and trying to educate myself the only culprit seems to be high Nitrates and Phosphates. My Phosphates where 600ppm so I did a Phosfree run and got them down to their current levels of 300ppm. As of today my current chem levels are as follows, done at my local pool store and backed up by my Taylor 2006 kit:

FC: 2 (I put in 1 gallon of 5.25% bleach last night otherwise it would be lower)
TAC: 2
PH:7.6
TA:90
CYA:60
CH:270
Salt:3500
Copper:0
Phosphates:300
Nitrates:60


PS: I had no issues last year at all and the pool was complete on Memorial day so we got to use it the entire season. I closed the pool in late October and I opened it in early April. I live in the Northeast specifically Northern NJ.

Thanks in advance.
 
Basically you need to SLAM Process your pool. You probably are fighting an algae bloom that has never gone away and so the SWG can't keep up. Also, I think your SWG is undersized. I have a pool half your size and I also run an IC40 as well. I'm definitely going to an IC60 in the future.

As for IntelliChem, I can't say much as I do not own one but you are correct, ORP doesn't work well with the high levels of CYA required for efficient operation of the SWG. You can read many, many threads about ORP's limitations for residential, outdoor pools. Honestly speaking, I would never spend the money on one because they just don't seem to work well.
 
marmo said:
I did Slam my pool last month following the instructions here using the calculator etc. I guess my question is, are the Nitrates or Phosphates the culprit because this is what Pentair and the pool store are telling me...
Click to expand...

Ignore the Pool Stores, they just want to sell you PhosFree which is, for the most part, unnecessary. I'm going to say something you probably don't want to hear, but I think the ORP system is more trouble than it is worth. If the ORP can't control the chlorine output properly, then it is very likely that your FC dropped below the recommended levels and algae got growing again. You may have clear water, but it is totally possible that you have algae growing in your water at a rate that the SWG can't keep up with. At some point, the algae growth is going to exceed the ability of the SWG to produce enough FC to kill it and you're going to go green again.

So, while it sounds like I'm telling you to waste all that money you sunk into an IntelliChem system, I would stop using it to control your FC. I would unplug it or disable it, SLAM the pool again and then set the IC40 into it's normal mode of operating on a duty cycle based on the percentage output. You can continue to use the acid dosing system to control pH but I would not rely on the ORP system to control FC, they are just too flaky.

My $0.02 opinion for whatever it's worth...
 
The other option for getting the ORP to work better would be to lower your CYA to less than 50ppm (like 30-40ppm) so that there is less interference of the CYA with the ORP probe. However, this means that your SWG will likely have to run very hard (100% output for much of the pump run time) in order to replenish FC that is destroyed by the sun. Again, given the size of your pool, I think a larger output SWG (an IC60) would have been a better choice. I know the IC40 is supposed to handle pools up to 40,000 gallons BUT, as in written about in great detail here on TFP, most outdoor pools can use larger SWG's to help reduce wear & tear and lengthen cell replacement intervals.
 
@YippeeSkippy, I understand but I have to keep ading bleach so than whats the point in having a SWG...

@JoyfulNoise , Yes I have read this about not worrying about phosphates etc and how the pool store just wants to sell you stuff, again I understand this. As far as not allowing the ORP to control the IC I understand this and I am fine with this but again as it is now the IC runs @ 100% all the entire 12 hours of filter time so whether I put it on a duty cycle or not it cannot maintain the FC.
 
marmo said:
@YippeeSkippy, I understand but I have to keep ading bleach so than whats the point in having a SWG...

@JoyfulNoise , Yes I have read this about not worrying about phosphates etc and how the pool store just wants to sell you stuff, again I understand this. As far as not allowing the ORP to control the IC I understand this and I am fine with this but again as it is now the IC runs @ 100% all the entire 12 hours of filter time so whether I put it on a duty cycle or not it cannot maintain the FC.
Click to expand...

Then here's what I would recommend by way of experiment. Turn off the ORP system completely, do an overnight chlorine loss test to make sure your pool water is still good and, if it is, increase your CYA to 70ppm. Then start running your SWG in it's standard mode (manual % output adjustment only). Start at 80% output for however many hours you run the pump. See where your FC is and how it changes throughout the day. Then, if you can better hold FC, start dropping either the pump run times or the % output to dial in the target FC.

Basically if you have to run your IC40 in manual mode at 100% for the entire pump runtime even with a high enough CYA to give you good UV protection, then I think you can honestly say that the cell is just undersized for the pool. At that point you can then look at options. The problem right now is that the ORP system is just adding too much variation to make any sense out of what it is doing. Take it out of the equation for now and you'll be better able to determine if the SWG is adequately sized.

This is a very common problem with pool builders that don't understand SWG's very well. They typically undersize them for the pool volume because they either don't know salt water systems very well OR they listen to the SWG manufacturers who want undersized cells because that generates more revenue. Cell warranties (when bundled with other equipment) usually max out at 3 years. So the big players do not want you using an oversized cell and getting 7 years out of it because that doesn't make them a lot of revenue. They'd much rather you purchase a smaller cell, burn it out in 4 years and then force you to buy a new one.
 
Also, when was the last time you took the cell out and cleaned it?

If you have not serviced the cell recently, I would also do that as part of the experiment so that you can be sure your cell is clean and working at optimal efficiency. If you have been running it hard at 100% output, the cell blades could easily be caked with calcium scale.
 
I did the bucket test @ Pentair's request to see if the cell is producing Chlorine, basically to see if it is working. I did this yesterday and the cell is clean, no build up on the plates. Bucket test was to put it into a 5 gallon bucket of pool water and hold down the flow sensor and see if it works and the answer is yes it starting producing chlorine.

I had a nasty algae outbreak earlier this year, wan't sure if it was mustard but I followed the slam procedure and even went as far to take out the lights and clean out the niches. Again I was thinking the cell had me covered but obviously not. Anyway after a lot of reading here and following pool school and the slam procedure I raised the FC to 20 for several days. Just to note I have I never had a high CC and you can rarely if ever smell Chlorine in the pool, only when I put in the bleach. At any rate when there was no algae left after 3 days I allowed the FC to drift back down to normal. But I've been struggling with this issue all season.

As far as the IC being undersized I'm not sure about that. I understand that it's better to be over-sized than undersized and I will go with an IC 60 next time. Just a note my pool is prob more like 28K but its hard to say because I didn't use a flow meter when filling and I have a very large beach/shelf 18" deep. area that takes up a good portion of the pool.

I'll do your test but if I just added a gallon of bleach yesterday does it matter? Also doing the "OCLT" should I have the filter running overnight?

NOTE we have thunderstorms in the forecast the next few days and it is now raining so not sure I can do a OCLT atm...

Thanks for helping.
 

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marmo said:
I'll do your test but if I just added a gallon of bleach yesterday does it matter? Also doing the "OCLT" should I have the filter running overnight?

NOTE we have thunderstorms in the forecast the next few days and it is now raining so not sure I can do a OCLT atm...

Thanks for helping.
Click to expand...

The OCLT is best performed by raising the FC up to 10ppm using bleach after the sun has gone down and then checking it again in the morning. Your pumps should running the entire time AND the SWG should be turned OFF. If you lose more than 1ppm overnight, then that indicates you have something growing in the water.

A little rain should not inhibit you from performing the test. Unless your pool water level is raised by several inches or overflows, rain has very little effect on chemistry. For example, 3" of water in my pool is ~5% of the total volume. It takes a torrential downpour to put 3" of water in my pool. Therefore I should care for my pool on the same schedule rain or shine since it doesn't really matter from the water chemistry perspective.
 
Okay I'll do it tonight. The Calculator states I should add approx 4 gallons of bleach to get it up to 10. I'll do that when I get home test it before I go in for the evening and than test in the morning and post back. Again thanks for the guidance!
 
marmo said:
Okay I'll do it tonight. The Calculator states I should add approx 4 gallons of bleach to get it up to 10. I'll do that when I get home test it before I go in for the evening and than test in the morning and post back. Again thanks for the guidance!
Click to expand...

Are you using PoolMath to get your dosing? There's an old site called poolcalculator.com which is no longer accurate. You should only be using PoolMath.



Sent from my iPhone using Tapatalk
 
I would suggest that after adding that much to your pool you let it circulate for 30 min or so then retest just to be sure of your starting level FC. Then tomorrow morning you test again to see what loss there may have been.
 
marmo said:
@JoyfulNoice, yes using http://www.troublefreepool.com/calc.html

@YippeeSkippy , thanks will add when I get home and wait at least an hour of circulation to test.

Question, I am assuming it does not have to be 10 on the nose and why 10? Why not 8 or 12?
Click to expand...

When you complete a SLAM, one of the criteria is that you pass the OCLT. This happens at shock level FC.

When your pool is running normally but you suspect a problem, an OCLT is a good way to see if a problem is brewing. OCLTs work best at elevated FC levels, so the recommendation is to raise the FC level up a bit. Most people can get to 10ppm FC pretty easily and, if there's nothing wrong, not having to drift back down from shock levels is a plus. There are other good reasons to only go to 10ppm such as still getting a reliable pH test and other reasons.


Sent from my iPhone using Tapatalk
 
I put in 5 gallons of 5.25% bleach. FC reading an hour later with good circulation gave me 21! So technically I'm slamming. Hopefully this won't screw up a 24-hour test but based on what you wrote I think I went to high, sorry about that. I'll let you know what the reading is tomorrow morning.
 
marmo said:
I put in 5 gallons of 5.25% bleach. FC reading an hour later with good circulation gave me 21! So technically I'm slamming. Hopefully this won't screw up a 24-hour test but based on what you wrote I think I went to high, sorry about that. I'll let you know what the reading is tomorrow morning.
Click to expand...

You're below your shock level FC (24ppm) so you'll be fine. Just make sure your pumps are running, the SWG is OFF and you measure tomorrow morning BEFORE sun hits your pool.


Sent from my iPhone using Tapatalk
 
15 FC this morning. definitely need to slam...
Going to Foodtown to go pickup a few cases of bleach.

I took care of my parents pool all growing up, fresh water, and never had an issue like this. Could it be that a plaster pool just allows the algae to Harbor because of its pouressness nature? BTW I have brushed my walls and floors like a bandit the last time I slammed and I just do it from time to time anyway...
 

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