SLAM

[Jean-ji]

SLAM time again. We were suspicious the water was slightly duller looking. We did the OCLT and we had a loss of 3.5.
The CYA is 70 and our chlorine has not gotten below 6. We’ve been cranking up the SWG though, which also made us suspicious.

We live in FL and had a heavy rain earlier this week. It’s been really dry with little rain before this week. I’m wondering if the rain washed in pollen etc that was on the cage into the pool. We do not run our sheer descent every day, could that allow stuff to grow?

We slammed two months ago when our CYA was down to 50 and the FC was 5. Again the water was not sparkly then.

We are maintaining our FC usually around 8 out of paranoia from a few SLAMs last year (again never green only a loss of clarity) and the lowest FC has gotten is 5.

I’m at a loss for why this is happening with the correct target and higher FC being maintained.

 

[Texas Splash]

I’m at a loss for why this is happening with the correct target and higher FC being maintained.

That can be a challenge, and not every scenario is identical. The inclement weather might have contributed to excessive organic dumping perhaps. It is important to run any accessories once a day or so to keep them well-chlorinated. Also remember that if you confirmed algae before, it was exceptionally important to ensure nothing was left behind by inspecting very carefully any potential hiding places for algae (i.e.. behind light, hand rails, steps, etc). During the SLAM period, if you haven't been doing it already, I would just leave the SWG off and use regular bleach.

 

[Jimrahbe]

Jean,

If you just did a SLAM two months ago and have algae again this soon, then either you have not been keeping your FC up to the required levels, or you never really completed the original SLAM, and still had some algae left in your pool..

I recommend that this time you SLAM a little harder and a little longer. If you think your CYA is 70, SLAM like it was 80 and go a full 24 hours longer than normal. Also, make sure you brush and follow Pats advice and look for hiding places..

The more you can keep the water at the SLAM level, the faster and quicker the SLAM can do its job. This can be difficult when working, but the further apart the chlorine doses are done, the longer it takes to SLAM.. Since your water is mostly clear this one should not take too long..

Thanks,

Jim R.

 

[Jean-ji]

We did complete the last SLAM with an OCLT loss of 0. The lowest FC has been 5 since then. I’m retired and add the chlorine every 2-3 hours during a SLAM. No SLAM have ever lasted overly long since we catch them so early.

I haven’t been running the descent or therapy jets every day and I will now. Even so, wouldn’t maintaining the correct FC take care of it? I would think they would take the FC down when opened and I would understand that. I let my FC get too low last year several times as a new pool owner last year and I understand getting algae then. I don’t get why it’s happening with maintaining target and higher FC now with all other pool chemistry within recommended ranges.

 

[Texas Splash]

I don’t get why it’s happening with maintaining target and higher FC now with all other pool chemistry within recommended ranges.

This can seem frustrating, but we know that algae simply cannot survive in a properly chlorinated environment. So if a pool has all algae completely eradicated at some point in the past and is squeaky-clean, then it would seem to reason that a new algae scenario would be attributable to one or more of the following:
- FC getting too low for the current CYA
- Inaccurate testing resulting in mismanaged levels (reagents old, etc)
- Unusual anomaly in weather or local situation where excessive organic material was introduced to the water
- This one is a stretch, but perhaps an untouched area in the pool, something hollow or hard to get to (i.e. behind light, hand rail, etc) where algae was either almost eradicated to a point that it allowed a pool to pass an OCLT. We use the OCLT as one measuring tool to pass the SLAM, but we also have the other two because a pool can show indications differently.

Maybe some of this will help to explain your scenario. Let us know if there's anything else we can discuss to help.

 

[Jean-ji]

We ordered a new chemistry refill kit when they were on sale and have been using that. I’m leaning towards the rain and organic material washing in and overloading. Also as I’m cranking the SWG to compensate, it’s probably covering up an ongoing loss.

Thanks for helping, it’s our second year and I’m still getting to know the quirks of our particular situation.