Can't get FC to drop in SWG pool

[PointeTaken]

I'll have to pull the readings for you when I get home.

My apologies, it’s an Aqua Trol not an Aqua Rite. Diagnostics:

Temp- 86
Voltage- 31.3 (not generating)
Current- 0.0 (not generating)
Desired output- 18P (but switched to off right now)
Instant salinity- 0
Product- AL-6
Software revision- 1.47

Double-checked the cell model. It is confirmed T-CELL-5. Wouldn’t surprise me if previous owner bought undersized replacement to save a buck. I’ve gotten the distinct impression from other things in the house that he was very much that way.

 

[PointeTaken]

How long are you waiting after FC test to test CC?

Virtually immediately

 

[JamesW]

Ok. Well, we know that the cell is not creating the fc increase. So, that indicates test error or someone is adding chlorine without your knowledge.

 

[PointeTaken]

Ok so I ran pump again today without the SWG outputting anything (off). I did another full battery test and this time made sure to really take my time and give it my fullest attention. There are a couple tests that I think I may have flubbed previously, including the CC. Here were my results just 45 mins ago, about half an hour after the pump shut down:

FC: 12.0
CC: 0.5
PH: 7.4
TA: 60
CH: 130
CYA: 40
Salt: this was the first test I did with an actual test kit, which finally arrived today. Up until now I was going off the SWG display. The test kit yielded 3800 ppm of sodium chloride. Yikes

Temp was 86.

I’m feeling a little more optimistic about things now. I’m going to do the FC test again tomorrow before the sun comes out and see if there was any overnight loss. Assuming that’s all good, suggestions for next steps? Keep the SWG off for another day? Water looks good right now minus a couple of bugs doing the backstroke.

 

[JamesW]

All of those numbers look fine. Let the fc drift down to about 4 to 6 for normal levels and you should be good.

 

[PointeTaken]

Water looks good right now minus a couple of bugs doing the backstroke.

 

[PointeTaken]

All of those numbers look fine. Let the fc drift down to about 4 to 6 for normal levels and you should be good.

When I crank the SWG back up, should I set output to 50% and see where it takes me?

 

[mknauss]

If you run the SWCG at 50% for 24 hours per day, it will create 3 ppm FC per day in your pool. With your low CYA, that may or may not be enough at this time of year. So test daily for awhile to see if adjustments need to be made.

 

[JamesW]

How many hours do you intend to run the pump?

I would start with the output at 100% and 12 hours of runtime.

 

[PointeTaken]

How many hours do you intend to run the pump?

I would start with the output at 100% and 12 hours of runtime.

It’s interesting, the previous owner said he always maintained his FC level at 4-5 and ran the SWG at 70% for about 8 hours a day. Indeed, my first initial test when I took over - if you refer to the original post - had an FC of 5. I know what the output numbers for the T-5 SAY should be expected, but in my head something isn’t making sense. Maybe I’ll run it at 70% again and see where that puts me. I have a few days to make adjustments before Labor Day . Either way, I told wife that they should be good to jump in tomorrow afternoon since FC is below the SLAM level for the current CYA. After Labor Day I may put another 10 or so CYA into the water.

 

[JamesW]

Move the switch to off for a minute and then back to auto and recheck the diagnostic readings.

What is the average salinity reading from the box?

If the salinity is higher than normal, the cell will produce more chlorine than the expected amount.

 

[ajw22]

Are you sure your pool is 15K and not smaller? A smaller pool volume would give more ppm output from the cell then we are calculating.

 

[PointeTaken]

Are you sure your pool is 15K and not smaller? A smaller pool volume would give more ppm output from the cell then we are calculating.

I’ve been wondering that myself because the math isn’t adding up. The bill of sale that was included with all the paperwork when we bought the house says 15K, but it wouldn’t be the first time a company lied or made a mistake. 15K could even be a size class, depending on manufacturer. When I did a rough Length X Average Width X Average Depth estimate it came to 14,456, which is what I have in the Pool Math app. It could still be way off. The pool is irregularly shaped in two dimensions (width and depth). I may split it up into four or five segments and total up the volume of each segment.

 

[PointeTaken]

The good news is that overnight FC loss was only 0.5.

 

[PointeTaken]

So, since the pool is irregularly shaped, I divided it into three segments, estimated the volume of each segment and added it all together. The result was 11,749 gallons. This of course doesn't even take into account the various steps, benches, and the safety ledge, all of which displace water and further reduce the volume. I don't know the exact size but it sure as heck isn't the 15K that the PB put on the bill of sale!

 

[frogabog]

You can sort out your volume with Pool Math. It's not that hard... you just add known % of chlorine, then test about 30-45 minutes later and check FC. Then, put that number into Pool Math "Effects of adding chemicals", and adjust your volume till the amount you added equals the result of your FC test.

You may be off by 200-500 gallons but if you want more precision just use the 25ml sample with the FAS/DPD instead of the 10ml sample.

I got mine within about 50 gallons with this method.

 

[PointeTaken]

You can sort out your volume with Pool Math. It's not that hard... you just add known % of chlorine, then test about 30-45 minutes later and check FC. Then, put that number into Pool Math "Effects of adding chemicals", and adjust your volume till the amount you added equals the result of your FC test.

You may be off by 200-500 gallons but if you want more precision just use the 25ml sample with the FAS/DPD instead of the 10ml sample.

I got mine within about 50 gallons with this method.

Excellent suggestion. With this method I came to 12,250 - 12,750.

 

[mguzzy]

It’s interesting, the previous owner said he always maintained his FC level at 4-5 and ran the SWG at 70% for about 8 hours a day. Indeed, my first initial test when I took over - if you refer to the original post - had an FC of 5. I know what the output numbers for the T-5 SAY should be expected, but in my head something isn’t making sense. Maybe I’ll run it at 70% again and see where that puts me. I have a few days to make adjustments before Labor Day . Either way, I told wife that they should be good to jump in tomorrow afternoon since FC is below the SLAM level for the current CYA. After Labor Day I may put another 10 or so CYA into the water.

I have a tcell-15 and I run my CYA at about 60 and it seems to do well. There is a feature in the Pool Math app that will tell you how much FC output to expect for the chlorine output of your cell, given sized pool, and runtime. It's quite usefull for getting a starting point on your pump runtime.

Also I figured out my pool volume by the chemistry as well. Its a free form shape and trying to use calculus or summing up semi oblate spheroids was too much work for my puny brain to process.

 

[aussieta]

i am thinking previous owner added an mps shock prior to you taking posession
this is what has messed up th cc levels

 

[PointeTaken]

CYA at 40 is lower than I’d like, so after Labor Day I’ll probably add 20 CYA. But, pool looks great now and was thoroughly enjoyed today! Thanks everyone for getting me up to speed on salt pools and TFP!