Help with pool SLAM

[dparker]

Hello all. My wife and I purchased a home over the winter with an in-ground pool. We are first time pool owners and figuring things out as we go. I have read pool school and slamming procedures. I also order the TF-100 test kit. My pool is crystal clear but I'm fairly certain I have mustard algae. It is growing on the wall and clumping on the floor in the shaded areas. My test readings are as follows:
pH: 7.2
FC: .5
CC: .5
TC: 1
CYA: 40

The problem is I purchased a 25 lb. bucket of sodium-dichloro-s-triazinetrione from InTheSwim before I knew I could use bleach. The pool match calculator is telling me I need 7 lbs of this product and I'm scared this will push my CYA too high. What should I do at this point? TIA!

 

[tim5055]

I would hold off on using the dichlor as it will push your CYA up.
You should read the directions on SLAMing your pool in the How To section of Pool School and follow that procedure completely to the end.

• CC is 0.5 or lower;
  
• You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
  
• And the water is clear.

When all three are true, you are done SLAMing and can allow the FC to drift down to normal levels.

Don't feel you are alone. I also made a big purchase of tabs from Costco before I knew about CYA.

 

[Divin Dave]

Hi dparker,
Im sure at some point when you learn a bit more, you can use the dichlor.

Tim gave some great advice and I concur with him.

as a FYI though,
at the bottom of Pool Math, is a Effects of Adding section. That is useful in dermining what will happen if you add x of this or that.

 

[duraleigh]

The dichlor is not wasted but do not use it for the SLAM. It will keep forever and, in your climate, you will get some dilution of CYA from rainwater.

When your kit comes in, please post up your own testing and then start from there. Do not be surprised if your testing disagrees with whatever was the source for these tests you posted.

 

[dparker]

These readings were taken with the Tf-100. I'm going to wait to the weekend before slamming. Thanks for the input thus far.

 

[gwc]

Hi dparker,
I understand wanting to wait until the weekend, but the FC is so low you can develop a lot of algae very quickly. I suggest that you add enough bleach to get enough FC to prevent an algae bloom. Personally I would get the FC to 8ppm until you SLAM the pool. You will have to check the FC level as frequently as possible to maintain that level.
Welcome to the forum and good luck.

 

[Patrick_B]

These readings were taken with the Tf-100. I'm going to wait to the weekend before slamming. Thanks for the input thus far.

Welcome to the forum dparker.

Whenever you get ready, let us know and we will help walk you through.

While you are waiting, take a look into Pool School and review SLAM again while you wait. Let us know if you have any questions in the meantime.

 

[dparker]

Ok so I've started the SLAM process. I started with these numbers:
FC:5
CC:.5
pH: 7.2
CYA: 40
After I added the bleach recommended to achieve shock level according to the CYA chart and pool math my numbers are as follows:
First 30 mins:
FC: 20
CC:1
I tested again within an hour and results were:
FC: 19.5
CC:1
My numbers aren't moving as expected did I do something wrong? I've read pool school, ABC of pool chemistry, and slamming. I've followed the instructions laid out in these articles. Thanks

 

[tim5055]

What do you mean "aren't moving as expected", what did you expect?

For a CYA of 40 your target is 16 FC. Every time you test it should be 16 or just a little higher. Large amounts over don't speed things up. If it's not 16 add bleach to get it there.

It should look like this
Test
Adjust FC
Test
Adjust FC
Test
Adjust FC
Brush

Test & adjust at least twice a day. More often helps. Brush at least once a day.

Stop when:

• CC is 0.5 or lower;
  
• You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
  
• And the water is clear.

When all three are true, you are done SLAMing and can allow the FC to drift down to normal levels.

 

[dparker]

Yeah I get that but why am I not having to adjust FC? It's holding steady I was expecting to have to add more chlorine after every test to bring the FC up. I think I calculated my pool volume wrong leading to the 20 instead of 16 shock level.

 

[tim5055]

Yeah I get that but why am I not having to adjust FC? It's holding steady I was expecting to have to add more chlorine after every test to bring the FC up. I think I calculated my pool volume wrong leading to the 20 instead of 16 shock level.

Tha t is how I narrowed down the size of my pool. Watching the effects of chemicals.

You lost 0.5 in 30 minutes

Just keep it above 16. When the pool is clear and you don't see any algae it's time to start watching cc & maybe and OCLT.

With a little luck your SLAM will go fast, some do.

 

[jblizzle]

In your first post you state that the water is crystal clear ... so there is not much in the pool to consume the FC quickly.

Just follow the process to hold 16ppm and brush really well where you have seen what you think is mustard algae. Then after passing the 3 criteria, boost the FC for a day as described in the Mustard Algae Article.