SLAM Question

[tdub4]

Started the SLAM process yesterday morning due to algae on the walls.

The target for chlorine based on the CYA was 18. Last night I tested before bed and was down a little to 16.2. I added the recommended amount to bring it back up and this morning was at 16.6. My question is this….should I add bleach just before going to bed or should I have let it go at the 16.2 overnight to see what the loss would be in the morning. Without testing again, after adding what I did last night, doesnt give me the actual drop overnight.

Make sense?

 

[mknauss]

Post a full set of test results if you could. Use 10 ml water sample for FC testing. Each drop to clear is 0.5 ppm FC.

No reason to do an Overnight Chlorine Loss Test until the pool is crystal clear. Is yours?

 

[Texas Splash]

Also be sure to reference the proper SLAM (FC) level on the FC/CYA Levels. There is no such level 18) on the FC/CYA Levels. Simply round the CYA up if needed, but don't try to split it. For example, if it looked like 45, call it 50 and SLAM at an FC of 20.

 

[tdub4]

Post a full set of test results if you could. Use 10 ml water sample for FC testing. Each drop to clear is 0.5 ppm FC.

No reason to do an Overnight Chlorine Loss Test until the pool is crystal clear. Is yours?

Thanks for the reply. A few questions:

Full set as in all numbers: FC, CC, PH, TA, CYA, etc?
Wouldn't some of those be affected now that I am 24 hours into the process?
I just added 37 ounces of bleach - I assume I should wait a few hours to test and post those results?
I have been using the 25ml sample (I can change to the 10 ml)...I assume the the 10ml would save on chemicals.

 

[tdub4]

Also be sure to reference the proper SLAM (FC) level on the FC/CYA Levels. There is no such level 18) on the FC/CYA Levels. Simply round the CYA up if needed, but don't try to split it. For example, if it looked like 45, call it 50 and SLAM at an FC of 20.

Gotcha. Yep - I called it 45 on CYA thus the 18 but will bump to 20.

 

[mknauss]

Full set as in all numbers: FC, CC, PH, TA, CYA, etc?

Yes. Only thing effected is pH if your FC is above 10 ppm at the time of the test. What was your pH before you started?

 

[tdub4]

Yes. Only thing effected is pH if your FC is above 10 ppm at the time of the test. What was your pH before you started?

7.2-7.4

 

[tdub4]

I ran the numbers at noon today. About 4.5 hours after adding 37 ounces of bleach this morning. At that point it was 16.6 FC and was targeting 18 (but now know I should be targeting 20). Here are the test results:

FC: 16.5
CC: 0
TA: 100
CH: 230
CYA: 50

I am in Texas, but it is overcast - no sun at all - and cool today (56 degrees). It appears I should be adding 92 ounces of bleach to get to 20 now.

 

[Texas Splash]

it is overcast - no sun at all

Here in the S.A area as well. Gloomy. The clouds and cooler weather work in your favor. So do your best, based on work schedule or access to the pool, to maintain that FC of 20. Be sure to review the SLAM Process page daily to ensure you are following all the other steps required. Be patient, it works.

 

[tdub4]

Here in the S.A area as well. Gloomy. The clouds and cooler weather work in your favor. So do your best, based on work schedule or access to the pool, to maintain that FC of 20. Be sure to review the SLAM Process page daily to ensure you are following all the other steps required. Be patient, it works.

Thanks. At what point should I consider cleaning the cartridges in the filter. I did a full breakdown and clean probably 3 weeks ago, but understand will now need to clean again to get dead algae (or active) off the filters. I am one day in to the SLAM...should I do that in next day or two? Or is that at the end of the process?

 

[Texas Splash]

At what point should I consider cleaning the cartridges in the filter.

We typically clean our filters when the pressure increases by about 25% from the clean pressure. If you have a large (over-sized) filter for your pool, hitting that 25% elevated mark may take a while, but you should see a gradual increases as the filter captures the dead algae.

 

[tdub4]

Quick question when using the pool math calculator....I am using the Walmart brand bleach (Great Value) that shows the sodium hypochlorite to be 7.5%. Am I correct in entering that 7.5% value in the "weight" field of the calculator? It seems to be accurate as far as my FC values after adding the suggested amount but noticed if I change the 7.5% to 10% in the calculator the descriptor changes from "weight" to "trade" which threw me off a bit.

 

[PoolStored]

Yep, just put in 7.5.

 

[tdub4]

New question...can/will CYA change during SLAM. It was pretty solid 45 at start, I would say it is now at 40. If so, should I be dropping back to the FC recommendations of 40 CYA (16 FC) or stay at the original 50 CYA (20 FC)?

 

[tdub4]

Update....this morning (Sunday) was first morning that FC level matched the reading for FC level last night (started last Monday). The pool is clear and CC is .5 or less. So a couple of questions:

1) Should I continue to keep the FC level within the SLAM numbers throughout today and test 1 more time in the morning to make sure I am good?

2) I have noticed that when testing the CC, it shows as clear when the water is being mixed (using the Taylor SpeedStir), but when the water settles and isnt moving there is a tint of pink in the water - normal?

3) This process is time intensive! I have always been a tablet (via chlorinator tube) and powder shock guy. I could go days/week between tests, but granted the water probably wasnt as sanitized as this method. Would like to make the switch to this method with bleach, but thinking that could be just as time intensive (as SLAM) and costly if I am needing to buy/add bleach daily (I understand the FC levels will be lower than SLAM at that point but seems I will need to test and adjust daily). Am I thinking about this wrong? We wont be adding a SWG so that isnt in the cards. Any feedback or thoughts are appreciated!

 

[mknauss]

Should I continue to keep the FC level within the SLAM numbers throughout today and test 1 more time in the morning to make sure I am good?

Not a bad idea.

isnt moving there is a tint of pink in the water - normal?

It is. Once the test is clear, the test is over.

Am I thinking about this wrong?

You do need to add chlorine daily, or as often as needed to maintain your FC in the target level for your CYA. You likely will get to know your pool and not have to test every day.

 

[duraleigh]

New question...can/will CYA change during SLAM. It was pretty solid 45 at start, I would say it is now at 40.

The test is not that precise plus or minus 10-15 is as good as it gets.

No one has yet asked I don't think......have you brushed the walls?

 

[tdub4]

No one has yet asked I don't think......have you brushed the walls?

Every day at least 2x

 

[duraleigh]

Good! What does your water look like?

 

[tdub4]

Water is clear. Second overnight test showed a drop of just 1 point (yesterday was same as previous night - no change) and no CC this morning as well. I “think” I am there. If so, I assume at this point I let the levels drop to normal range for my CYA and adjust accordingly to get everything (i.e. PH) back in line - correct?

(ETA: pic below shows as more dull/slight tint vs sharp color from original photo)