How much should swg runtime increase with temp/sunlight?

[MattM]

First season, we had some issues with cya disappearing from pool earlier which made it hard to get a good estimate of what the SWG runtime should be as our pool water heated up from 55 degrees to now where it peaks at ~89 degrees for 6hrs each afternoon before falling back to 84 degrees overnight. I shocked the pool nicely last month, and was able to maintain FC > 5 (mostly 12-16 during shock) for ~3 weeks with our ic60 swg running between 37-40%. No bleach after initial. Then pool was stable at normal FC levels (4-6.5) for another 2 weeks and I left pool cover open to bleed off chlorine.

Yet, this week - with pool covered nearly all the time - the FC has been dropping consistantly while I push up the SWG runtime....
approaching ~50% now
FC was 2 this afternoon
CC's/Chloramines still staying at zero
Pool is sparkingly clear
cya level should be between 30-40
pool is covered for all but ~4hrs/day
Kids and guests swim for 1-2hrs/day
Usually 2 people in pool, sometimes 7-8

I'd rather not bump up CYA > 40 given there is an intellichem attached
The <6 month old IC60 should be more than capable of managing our needs, I assume...pool is only 24K gallons.

Would it be abnormal if the pool requires pushing the ic60 higher? It seems excessive for our size pool. What would be a realistic target given our constant high pool temp and san diego sunlight/all year swimming weather?

more info: pump is on for 12hrs/day, SWG for ~11hrs

Note sure if this is related -- we've had some white flakes entering the pool from the returns a few times/week (unknown trigger, easily cleared up, looks like slightly dirty salt/sand..but doesn't disolve and tends to stay near drains, different sizes ), possibly ch clean cycles from swg? Could also be DE from filter cleaning before shock. Pool CH is ~320, csi just barely negative

Adding 2 big jugs of bleach to pool for time being to bring FC up to ~8 while I adjust swg runtime more...

 

[JasonLion]

I suggest doing a visual inspection of the SWG cell plates for possible scaling. If you spot any white crusty deposits the cell will need to be cleaned and you may need to adjust levels to avoid a repeat occurrence. If that doesn't turn up anything, the next thing to try is an overnight FC loss test to see if there is a low level algae problem.

 

[MattM]

I've thought about cleaning, but the acid injection from intellichem just before the SWG should have been sufficient to prevent that....but I guess opening it up and inspecting could be a good next step. I've never taken the ic60 offline before...I'll need to read up on it. So, if there is significant calcium deposits on it...than after cleaning I'll need to see if the system was in a negative feedback loop.....calcium -> increased runtimes -> more calcium -> lower efficiency/FC -> ever higher runtime... I assume this is something I should be able to handle entirely on my own? For cleaning, any jug with heavily diluted acid poured down the middle of the unit?

 

[JasonLion]

Your slightly negative CSI alone should have prevented scaling. The only suggestion of scaling is that your symptoms match scaling, but everything else suggests against it. It is easy enough to check, so worth checking anyway. The acid injection rate is most likely too slow to do much to prevent scaling of the SWG. You want it slow or your risk other problems.

Cleaning the cell is easier if you have the correct plug for the end of the unit. That lets you fill it with an acid water mixture and let it soak for a short while.

 

[MattM]

Thanks - I've sent an inquiry about the end cap to my pool builder. And, I'll review the ic60 manual before inspecting. Will post what I find.

 

[OperatorX]

You can get the cleaning kit from Amazon - that's where I got mine.. PN in the manual is: P/N 520670. Cleaning is simple. You use a hose to blow out any loose garbage in the chamber and on the blades. You put the cap on one end, then mix 1qt of Muractic Acid to one gallon of fresh water. Then, carefully pour that, or use a cup to pour into the chamber. If dirty, you should see bubbling within a minute. Leave the solution in the chamber until bubbling ceases. If you do not see any bubbles, you are good and empty the chamber right away. Then, use the hose to rinse down the chamber and blades throughly. Apply some silicone to the rubber O rings on the SWG and put back in line. Takes less than 20 minutes.

 

[MattM]

Thanks for the P/N - I ordered it. Hopefully won't have to do this more than every six months.

 

[OperatorX]

You don't mention your pH level. I tend to see what you are describing collecting in the pool when pH gets too high. Keeping it lower (7.2) tends to eliminate that for me. It could be what you are seeing. for what it's worth, I ran my IC-40 last season for 12 hrs a day in the 50-60% mode and it did fine. CYA was about 40 at that time. I'm raising it this year to see if I can reduce the amount the SWG runs.

 

[MattM]

I actually have lowered the pH to see if reducing the CSI would make it go away....too early to tell but it might be working. I started the season with a ph of 7.6, and then as I've added borates/cya and as the pool has warmed up, have had to go lower so that it is now at 7.3. I am worried about TA but I'm hoping muriatic acid over time will solve that...currently the tf100 TA test shows 160 and pool CH is ~320.

 

[MattM]

As a followup:
white flakes went away when I moved CSI to float between -0.2 to -0.05 instead of hovering between -0.07 and 0.
TA has also decreased by 40 points due to high winds the last few weeks and my opening up pool cover every afternoon (190 -> 140). Still, a long way to go though.
Pool FC has also improved, able to maintain FC between 4.5 - 8 easily. I did increase CYA to 45 which is about the most I thought I could push with the intellichem.
On the other hand, it looks like whatever calcium was being stored in those flakes or at the SWG has re-entered the water. Pool CH has spiked from 310 to 360 if I did the last CH test right.