Having to SLAM but not really sure why...third time now

[Auburn02]

My story sounds pretty familiar to that of @C3Cl3N3O3 in this thread, except for the whole opening the pool bit.

History of my test results going back a month:

	1 month ago	26 days ago	20 days ago	16 days ago	11 days ago	7 days ago	3 days ago
FC	5.5	5.5	6.0	5.5	6.0	5.0	4.5
CC	0.5	0.5	0.0	0.0	0.5	0.5	0.0
pH	7.5	7.6	7.8	7.8	7.5	7.6	7.7
CYA	60	DNT	DNT	60	DNT	DNT	DNT

At this point (this past Saturday afternoon), the pool for the first time had a cloudy appearance and brushing resulted in some puffs of green off the shelf and the floor. Well Crud. I added about a half gallon of 10% chlorine to bump it up, knowing we would be swimming on Monday (Memorial Day).

2 days ago (morning of Memorial Day - pool still not "clear" but no puffs of green when brushing)
FC: 5.0
CC: 0.0
pH: 7.8

Then yesterday, came home from work, water a little cloudier still and visible green on the bottom along the liner seams and in the corners. What the heck! Tested yesterday evening and numbers still look good
FC: 5.5
CC: 0.5
pH: 7.8
TA: 70
CYA: 60

Decided to do an OCLT, tested once more after sunset
FC: 6.0
CC: 0.5

Then tested just before sunrise this morning
FC: 5.0
CC: 0.5

So there's the 1.0 drop overnight, all other numbers still look (and have always looked) to be within spec, but nevertheless the water is not clear and I've seen green algae when brushing (and even when not brushing), so today begins my first SLAM which hopefully won't take too long.

Now the question is why? Where did I go wrong? The only thing "off" about this past week is on Thursday night I left town, and our power went out. It was out for about 6 or 8 hours. I came home late Friday night and didn't think about it, and it was about a day later I remembered the power outage and had to go reset my intermatic timer that drives the SWCG. So based on the outage of say 8 hours, that would mean there is a chance that the SWCG ran very little or not at all throughout the day Friday and part of Saturday until I reset it all Saturday afternoon, but when I did so was when the FC still measured 4.5. So maybe it dropped a bit below that, but still should not have been anywhere below the minimum recommended 3.0 for my CYA level of 60. Any other thoughts on what may explain it?

I guess once this is cleared up I'll work on keeping FC closer to the high end of the recommended range, which was always sort of my plan but when I test it and it's at 5 or 6 I don't bother to try and force it up to 7-9, but maybe I need to get it there and keep it there as a buffer but I'm still at a loss for why I'm seeing what I'm seeing if it never dropped below 4.5 in any test.

Happy to have any thoughts you all might have, and I'll update here the next rounds of test results and what I see.

One other question, once the algae is dead and settled, should normal brushing/filtering/backwashing and running my Dolphin S300i around be enough, or will I need to break out the vacuum hose? I'm really hoping to not have to do that, but if that's what it takes so be it.

 

[Texas Splash]

Why did this happen? Hard to really know. Your numbers overall do look very good. Did the power outage somehow increase the chance of algae, even if it tested well upon your return? Maybe. Perhaps the lack of circulation caused some dead spots in the water allowing green to grow. But for sure if you see algae you know you need to SLAM and maintain it until you pass all 3 criteria. Hopefully it will be a very short SLAM for you.

 

[Auburn02]

Perhaps the lack of circulation caused some dead spots in the water allowing green to grow.

Thanks Pat - to your point about the circulation, the outage was between about 10 pm and 6 am, when my pump doesn't run anyway. But it brings up the fact that I currently run the pump about 10 hours a day (8 am - 6 pm), with the SWCG running for about 9 of that (8:30-5:30). Maybe I just need to ramp it up to a longer run time at low RPM and turn down the SWCG dial to keep the daily output about the same, at least then even with an outage when power is back on it's more likely to be running and making chlorine in some quantities. Just another thought.

 

[C3Cl3N3O3]

Yeah your algae bloom in a well-maintained pool has parallels to mine.

One adjustment I'm going to make is to pull the pH back down weekly instead of as needed. I don't think it is a coincidence that the bloom struck when my pH was up to 8.0 or 8.1. Chlorine is more effective at the lower pH values, so the low FC / CYA values that I run make make me vulnerable. I'm going to increase the CYA to 35 as well.

My pool sucks 3 ppm chlorine during full sun on a good day so that also puts me at risk of falling below the minimums.

 

[Auburn02]

Odd (maybe, maybe not), I lost more in last nights OCLT than the first one, down from 23.5 to 21.0. But no green in sight at least, just cloudy blue.

And I’m about to be out of R-0871, so that stinks. May have enough for one more test. I have a bottle on the way but looks like tomorrow before I’ll get it. Wonder if I can pick up a bottle of just that at Leslies or Pinch-a-Penny.

 

[Texas Splash]

Wonder if I can pick up a bottle of just that at Leslies or Pinch-a-Penny.

They probably won't have it. For today you can use the 5 ml water sample size where each drop equals 1 ppm of FC. That may help you a little.

 

[CrystalRiver]

Odd (maybe, maybe not), I lost more in last nights OCLT than the first one, down from 23.5 to 21.0. But no green in sight at least, just cloudy blue.

Below FC 10, accuracy is plus or minus one drop. Plus or minus 0.5 ppm, with a 10 mL water sample. Above FC 10, accuracy is limited to 10%. That means, with a reading of 22, the true FC level is actually somewhere between 20-24. So you're still within the margin of error for not having too much overnight loss, but you are also within the margin of error for failing OCLT, as well (and always will be with FC above 10).

Regardless, you know you still need to SLAM until your water is back to its TFP self.

As for why this happened in the first place, I'm seeing several posts like yours this year. Variations on "I run my FC below target but never below minimum, why do I have algae?" All I can suggest is to try not to let FC dip below the bottom of the target range.

 

[Auburn02]

And now my pump has shut down.

Asked my wife to add some chlorine while I'm at the office, told her "just pour 32 oz into the flow of running water in front of the deep end return." "Okay. But the water isn't running." She checked and the breaker was tripped, she reset it, pump just shows Err 000f - manual says "Absolute AC Under Voltage Detected: This indicates that the supply voltage has dropped below the operating range of 99v. This could be caused by normal voltage variation and will clear itself. Otherwise there could be excess voltage sag caused by improper installation or improper supply voltage." Reset the breaker several times, same result, even left it off a few minutes and reset it, no change. I've read tales of some of these pumps being fussy about the breaker and needing a very specific Pentair brand breaker, not sure what mine is. But I'll head home shortly and try to cycle it a few more times and I guess if no change I'll be ordering a breaker. Unreal.

 

[Texas Splash]

@Jimrahbe are you familiar with Pentair issue?

 

[Auburn02]

Well now that I’m home I realize the breaker trips within a second or two after resetting it. So that’s obviously the problem. Curious that the pump still has “power” with it tripped, at least enough to display the error on the screen. It must have an onboard battery perhaps to last for a bit. Guess I’ll find out.

Called my builder who agreed the breakers are Crud, should have the electrician out tomorrow or Saturday to replace it. And I’m sure it still won’t be a Siemens/Pentair breaker so I’ll probably replace it again myself down the line.

In the meantime I’ll continue manually dosing and brushing to mix up the water and run the robot, but the filtering will just have to wait.

 

[Texas Splash]

Jim seems to be away for a bit. Let's try @JamesW.

 

[C3Cl3N3O3]

Does that control panel really run the LCD off battery backup?

Or is there something sketchy going on with the circuit(s)?

 

[Auburn02]

It must have something, the screen was lit up after the breaker was completely off but when I checked again 15-30 minutes later it was off.

I also was pleasantly surprised to find that after the power outage that affected my intermatic that drives the SWCG, I had to reset the time on the intermatic of course but the time was still set correctly on the pump. So there’s something there for sure.

I really hope my builder/his electrician doesn’t plan to charge me for this service call. I’m plenty capable of swapping out a breaker, but this whole pool is only 5-6 months old.

 

[Rocket J Squirrel]

Pentair pumps retain power for clock & settings for a surprisingly long time using a capacitor. There is no backup battery.

 

[Auburn02]

Breaker replaced and pump restored on Saturday, kept my FC up throughout by adding chlorine and mixing the pool by brush. Water is clear and CCs are 0.0, hopefully tonight’s OCLT is a success and I will let the FC drift down for another day or two (current FC is 19.5) and fire up the SWCG.

 

[Auburn02]

Grrr. I just ran out of R-0871 this morning. I had a new bottle on hand but it’s apparent that the new and old bottles have different effectiveness, which seems odd given my old bottle was less than 8 months old. Here’s what I mean:

Last night with the old bottle, FC was 19.5 (38 drops on a 10mL sample).

Just now doing the morning test, I ran out after 10 drops, opened the new bottle and added 21 more for only 31 total, 15.5.

Decided to do one more test with new R-0871 only, this time it took only 27 drops, 13.5.

So this appears to invalidate my OCLT, will have to do another tomorrow. In the meantime if the new bottle is to be considered the more accurate, I was never quite at SLAM level and am certainly not there now. Frustrating.

 

[Texas Splash]

Bummer, but good you caught the issue. Do you keep your reagents stored inside?

 

[Auburn02]

Yep, always inside.

The pool is clear and CCs are 0, but I’ll still add a half-3/4 gallon of chlorine to ensure it stays on the higher side throughout the day. Not going to try to get it back to 24 for now.

 

[Texas Splash]

I haven't looked back at this entire thread, but is everything removed from the pool? No ladder or steps in there are there?

 

[Auburn02]

I haven't looked back at this entire thread, but is everything removed from the pool? No ladder or steps in there are there?

Oh yeah, we don't even have a ladder and the steps are inlaid vinyl, no railing. Lights are surface mount/microbrites, other than that there's just the skimmer, the few return eyeballs and the main drains. There is really nowhere for it to hide, and I don't actually think there's anything organic left there.

If my original bottle of R-0871 really was less effective/potent which it seems possible given this morning's results, maybe that's how I got in this situation in the first place? I thought I was maintaining the FC between 4-6, but maybe in reality it was actually lower than that? Grasping at straws, but it's a theory at least.