Slam?

[Djones5548]

I have been using the site for a while and on my second pool. Just now having my first problem. Water clarity is fine. Numbers seem ok. However, my chlorine keeps dropping and dropping. I'm now at the point where my SWG is at 40% and still supplementing with liquid as my FC will drop to 2 in about three days. So visible signs of algae.

FC 5
PH 7.8
TA 100
CH 250
CYA 60
Salt 3600

I know my CYA should be a little higher but I've been thinking I may need to slam. Suggestions? I plan on dumping PH and bringing FC up to 20. My overnight test I only lost 1ppm and zero combined. Appreciate any advice.

 

[JJ_Tex]

Seems like a reasonable plan to me. You barely passed the OCLT, and looking over your logs I see you dropped below the minimum FC on a regular basis. My guess is that you are at the early stages of something. Hopefully bringing it up to SLAM level kills the stuff starting to brew in your pool and you can quickly get back to normal levels and your SWCG will keep you there.

How long are you running the pump, and I'm assuming the cell is working properly?

 

[wireform]

As JJ suspects early algae rearing it's ugly face. Slam and when done follow below:
The OCLT looks like you passed as long as it came along with all 3 criteria. Being it's mid summer with the sun high it would seem you should be closer to 80 CYA and start with the SWCG on the high % side and back it down till it compensates for daily loss.

 

[Djones5548]

Sounds good guys. I think the clear water was giving me hope but as stated my chlorine loss is obviously not normal. My pump runs 8 hours a day. According to pool math 20% on my ic40 for 8 hours should be sufficient. I'll start a slam today and see what happens. Appreciate it.

 

[Newdude]

I think the clear water was giving me hope

Unless it appears on surfaces, you cannot see it in the water until it is pea soup. It grows exponentially so that last step to visibility is a whopper.

Regular testing will give you plenty of advanced warning like you’ve seen. And well done !!

Step 1). Clear what you have with SLAM Process
Step 2). Raise the CYA. For Mid-CA you may even need to go to 80 if it doesn’t hold the FC well at 70, But we’ll cross that bridge when we get there.

Also, don’t hesitate to raise the SWG run %. Too many people get caught up in extending the cells life. And they are right, but not in any quantifiable way. An extra hour of runtime for a week takes a whopping 7 hours off the 10k hour expected lifespan. Mere peanuts. Even if you did it frequently you would never know that you reached end of life 350 hours early. Your efforts and monies on liquid chlorine to save those hours would wash in the end.

My $1500 unit (complete with controller, next time will be cheaper with only the SWG) will cost me about $0.15 an hour to run in life expectancy. Yours will be similar so when you weigh those costs against the liquid chlorine needed to supplement, It’s at least a wash and may even be cheaper to up the run time. The convenience factor tips the scales in the SWGs favor to just let it do it’s thing.

 

[Djones5548]

Checking back in for advice. Been running the pump 24/7 and maintaining 20 FC by making smaller additions every few hours. I've been doing OCLT and coming up right around 1 with zero CC. My morning test has been after sunrise but the sun is not directly on the pool. I didn't think my water was cloudy prior but it definitely seems clearer to me than a few days ago.

Today I wasn't able to check throughout the day and I ended up down to 14 FC for a loss of 6 ppm from my morning addition. My water temperature is in the mid 80s and my pool gets a lot of direct sunlight. I plan on keeping the slam going for another couple of days and hoping to get OCLT to . 5 or zero. My question is, is a loss of 6 ppm high? Since I usually run the SWG I'm not really sure. Also, when I stop the slam, do I leave the SWG off until FC drops back down under 10 and then kick it back on?

 

[mknauss]

My question is, is a loss of 6 ppm high?

It is. I would think you should be around 4 ppm per day. But your CYA may be a bit low, and raising it once you clear the SLAM criteria will help.

 

[Djones5548]

Yes, I'm planning on bringing it up to 70-80 as soon as the slam is done. I just don't want to stop the slam too soon.

 

[Newdude]

Checking back in for advice. Been running the pump 24/7 and maintaining 20 FC by making smaller additions every few hours

Great job !!

I didn't think my water was cloudy prior but it definitely seems clearer to me than a few days ago.

Wait till you see it ‘TFP’ clear. It has redefined the word for every last one of us. I like to call it stupid clear. You’ll know when you see it.

I just don't want to stop the slam too soon.

This is a very common mistake. By the end it is sooooo much easier to keep it going than it is to start another one in a week or three. Again, great job !!