Effects of Temperature on SLAM?

[goober07]

An alternate title would be "lessons learned" or "how I overshot my SLAM"

First year opening our in-ground, vinyl pool. Hasn't been opened for at least two years (we bought the house in April 2015, and the previous owner didn't have it open the season before either). This forum has been great so far.

However, me trying to be a cheapskate and conserve R-0871 reagent lead me to follow this line:

One indicator you can use is the color of the water. As long as the water remains a rich green, wait one hour and then assume that FC is zero. The algae will start turning gray or white when the FC level starts holding.

http://www.troublefreepool.com/threads/3913-Turning-Your-Green-Swamp-Back-into-a-Sparkling-Oasis

	4/23	5/1 15:15	5/1 16:00	5/1 16:40	5/1 18:00	5/2 7:00	5/2 18:00
FC					49	42.5	36
PH	8.2+	7.8	7.5	7.35		7.5	7.2
TA	30	40		80
CH	100
CYA	assumed 0				70*

Basically, I used 8 lbs of dichlor and 2 gallons of 12.5% bleach (2 lbs at a time, 45 minutes apart) to lower PH, add CYA, and add FC. I added 12lbs of baking soda to help bring up the TA, and 4lbs of granular CYA which

can take CYA up to a week to dissolve.

Poolmath and my 20k gallon estimate should have put my CYA at 40.

I finally decided that after all that chlorine, I should be testing even though things were plenty green. 98 drops of R-0871 later :-( the FC is way too high. Fortunately, the granular CYA dissolved by 18:00 (I hose clamped an old T-shirt into a bag in front of the return jet). But the reading is also questionable because it was my first test and the cloudy water throws it off.

I've resorted to 5ml samples and counting each drop as 1ppm instead of 10ml and .5ppm. I got the impression I'd be blowing through chlorine. Nothing I can do but let it float down (cloudy Ohio isn't helping). Is the 53F water temperature slowing down the slam, or is this the normal rate?

 

[PAGirl]

Please, please reread the SLAM process! You run the risk of damaging your liner with the chlorine that high......

Pool School - SLAM - Shock Level And Maintain

 

[jblizzle]

Is that quote really a part of that swamp thread? If so we need to change that. You should always be testing your FC level before adding any more chlorine. At colder water temperatures the chemical reactions are slowed down some.

 

[Donldson]

Hi neighbor (between Fremont and BG here). Since you added dichlor right away you had some CYA in the water and probably didn't damage anything, but yeah, be careful with that. I would have also checked for ammonia before putting a stabilized chlorine in, but given it was closed for so long any would have likely dissipated and you are clearly holding an FC now. The temperature is actually working in your favor, algae pretty much won't grow when the temperature is below 60 so you aren't fighting growth, just killing what is in there.

Remember, it took two years to get this way, it could be a lengthy process to clear it. One thing recommended is to take pictures so even if you don't notice the change in water color day to day you can look back and see it in the pictures. Actual chlorine usage can be weird, but as long as you are maintaining the proper FC for your CYA then it will eventually clear up.

Oh, you can stop measuring anything but FC and CC for now. Your pH is not going to measure right above 10 FC, just leave it be until after the SLAM.

 

[PAGirl]

Is that quote really a part of that swamp thread? If so we need to change that. You should always be testing your FC level before adding any more chlorine. At colder water temperatures the chemical reactions are slowed down some.

Not entirely.... Here is the whole section.

The very first time through the cycle you can assume that the FC level starts at zero. After that you want to test the FC level and only add as much chlorine as needed to bring it back up to shock level. PoolMath is very handy for this since you can enter your pool size, the test result in the Now column, and shock level in the Goal column, and it will tell you how much bleach to add.

The first few times the FC level is likely to be either zero or quite low. Once the FC level is still a substantial fraction of shock level after half an hour, you can switch to waiting one hour between tests.

If you don't have a test kit that can reliably measure high FC levels you will need to do some guessing. One indicator you can use is the color of the water. As long as the water remains a rich green, wait one hour and then assume that FC is zero. The algae will start turning gray or white when the FC level starts holding.

During the first half hour wait, get a skimmer net and remove everything solid that you can from the pool. If the algae has only been growing for a couple of days that might not be very much, but if the pool has been closed for a while there may be lots of leaves and other debris in there. Be as through as you can, given that you probably won't be able to see what you are doing.

 

[jblizzle]

Yeah I don't like that and I think we might need to change it

 

[goober07]

Is that quote really a part of that swamp thread? If so we need to change that. You should always be testing your FC level before adding any more chlorine. At colder water temperatures the chemical reactions are slowed down some.

To be fair, the swamp thread clearly says "you want to test the FC level and only add as much chlorine as needed to bring it back up to shock level," after the first cycle. I went on to read about the algae turning grey/white and thought I could get by saving a few rounds of testing. My water started off quite green, and I thought it made sense that any chlorine added would quickly be "swamped" (bad pun...)

Hopefully I haven't damaged anything. I couldn't find liquid stabilizer locally, which is why I went with dichlor. I didn't want to start SLAM without any CYA, but the 4lbs of CYA I added after the dichlor seemed to disolve really quickly. I thought it would take a week.

Edit: Opening, for reference
View attachment 47445
Edit 2: Down to 33ppm this morning - no idea why the iPhone inserted the opening pic correctly and this one upside down...

 

[kimkats]

I am glad to see the progress! Have you been brushing the pool? Try for at least once a day. It will make it look worse but is oh so needed.

Kim (yeah we do not know why some pics turn sideways or upside down)

 

[goober07]

I am glad to see the progress! Have you been brushing the pool? Try for at least once a day. It will make it look worse but is oh so needed.

Kim

Absolutely! Brushed it twice on opening day and once per day since. Also fumbling around the deep end with a leaf net pulling solids out.

 

[Swampwoman]

Goober, the faster you hand rake those solids, the quicker your Slam...been there, done that

While we don't recommend overdosing, at least you're nailing the "maintain" part of the slam! When it does drop down, be sure to stay a bit above your CYA:FC slam level to finish the process...remember that with higher cya than you intended, your level to maintain the slam will also increase (see link in signature re cya:FC ratios, normal and slam)

Cheers to clear and welcome to TFP