Help for SLAM this weekend

[KurtsPool]

I'm a first time pool owner as of October 2020. Things had been going okay and the water was clear until last weekend. I spent some time brushing, emptying baskets, and added some chlorine. A few hours later I notice that the pool was cloudy and had a green color, it has since gotten greener.

A friend of mine, who recently successfully SLAMed his pool, offered to help. Last night we tested the water, he has the TF-100 and I have the K-2006C, here are the results:

FC 0.5
pH 8.2
TA 130
CH 275
CYA 110
I believe temperature is about 55

My main question is surrounding what seems like an extremely high CYA. We used the pool math calculator which says I need to add 15 gallons of 10% chlorine to reach the SLAM target FC of 43. I would honestly prefer to spend a few hundred dollars on chlorine than have to drain and refill a significant portion of the pool to bring the CYA way down. Am I missing anything here? Can I just SLAM the pool and then gradually bring the CYA down while still safely using the pool?

We did add one gallon of acid last night.

 

[YippeeSkippy]

Hi there Kurt
I'm sorry to read that you need to do a SLAM process, but I can see why since your CYA is so high and your free chlorine (FC) is almost non-existent. You've been using chlorine pucks, I take it?? Yeah...those things are renowned for ruining a good batch of water. Darn it!

You're going to have to drain water and replace with fresh. Otherwise not only will your SLAM FC be super high (43 you say) but your day to day FC level will also be higher than you probably want to deal with.

CYA *only* leaves the pool via water exchange or splash out..... a very minute amount each month degrades but by the time you wait *that* out your pool will be growing trees in the swamp.

How often do you test your water?
Have you read the A,B,Cs of pool chemistry yet? ABCs of Pool Water Chemistry
SLAM Process

Does this make sense? If not, just ask.

Maddie

 

[mknauss]

It is not realistic to perform a SLAM Process at that level CYA. FC testing would be problematic. Is the cost of your water that high? In your area I would suggest an exchange rather than draining. See Draining - Further Reading

 

[Newdude]

Shameless plug to consider this your excuse to get a SWG, You’ll only have to exchange 37% of your water to get the CYA down to 70, instead of 73 % to lower the CYA to 30. And when you’re done...... you’ll have a SWG and it will be spectacular.

 

[KurtsPool]

Hi there Kurt
I'm sorry to read that you need to do a SLAM process, but I can see why since your CYA is so high and your free chlorine (FC) is almost non-existent. You've been using chlorine pucks, I take it?? Yeah...those things are renowned for ruining a good batch of water. Darn it!

You're going to have to drain water and replace with fresh. Otherwise not only will your SLAM FC be super high (43 you say) but your day to day FC level will also be higher than you probably want to deal with.

CYA *only* leaves the pool via water exchange or splash out..... a very minute amount each month degrades but by the time you wait *that* out your pool will be growing trees in the swamp.

How often do you test your water?
Have you read the A,B,Cs of pool chemistry yet? ABCs of Pool Water Chemistry
SLAM Process

Does this make sense? If not, just ask.

Maddie

Hi Maddie,

I haven't used any pucks but I believe the prior owner was since they have one of the dispensers in the pool (its been empty since we moved in). The only thing I have added is PoolLife TurboShock which was recommended by a reputable local pool supply store.

I have not been testing my water often enough but will be doing it 1-2 times per week once this issue is resolved. I have read through the A,B,Cs but admittedly it's a bit much for me so far.

I have two issues with the drain and refill, one is the price of water and the second is that I don't have a traditional sewer cleanout to drain into. But it sounds like it needs to be done.

 

[KurtsPool]

It is not realistic to perform a SLAM Process at that level CYA. FC testing would be problematic. Is the cost of your water that high? In your area I would suggest an exchange rather than draining. See Draining - Further Reading

Hi Marty,

I'll get over the cost of the water. I also do not have a good sewer cleanout that I can drain into. City says water needs to have no chlorine or algae to drain into storm drain. Any thoughts?

Thank you

 

[KurtsPool]

Shameless plug to consider this your excuse to get a SWG, You’ll only have to exchange 37% of your water to get the CYA down to 70, instead of 73 % to lower the CYA to 30. And when you’re done...... you’ll have a SWG and it will be spectacular.

Interesting idea. I believe my goal CYA is 45?

 

[PatricksPool]

I SLAM'ed at 100 CYA, it took a lot of bleach but it did work. With the FAS-DPD testing for FC is the issue that it takes a lot of reagents, or it's not accurate after a certain point?

 

[Newdude]

Interesting idea. I believe my goal CYA is 45?

30 for chlorine, 70 for SWG. Possible minor adjustments for both in the upwards direction after seeing how it responds to the UV demand.

 

[mknauss]

City says water needs to have no chlorine or algae to drain into storm drain. Any thoughts?

Not possible. If no chlorine, you have algae.
Every home has a sewer cleanout. Look around the house, typically street side.

 

[mknauss]

With the FAS-DPD testing for FC is the issue that it takes a lot of reagents, or it's not accurate after a certain point?

Error gets large. It is possible, but not very efficient. The amount of potential waste of liquid chlorine (at $5 per gallon or more right now) adds up.

 

[mknauss]

You need to target a CYA of 30-50 ppm for SLAM and future maintenance if using liquid chlorine. You will add liquid chlorine DAILY during summer.

 

[YippeeSkippy]

If that Pool Life Turbo Shock was a granular product it too contained CYA. All granular products contain either CYA or calcium.

If you can't find the clean out, how about running a hose to the street?

Maddie

 

[KurtsPool]

If that Pool Life Turbo Shock was a granular product it too contained CYA. All granular products contain either CYA or calcium.

If you can't find the clean out, how about running a hose to the street?

Maddie

It's illegal to dumb to the street unfortunately unless it is completely free of chlorine and algae, I was able to borrow a submersible pump but I'm SOL at the moment. I spoke with a pool maintenance company and he recommended getting the water tested for phosphates as it's apparently a big issue here. I've read the article here on phosphates and know that the water exchange is the right thing to do long term but I need to figure out how to get rid of the water.

 

[YippeeSkippy]

You say your FC is 0.5, right? That *is* basically ZERO chlorine. Your tap water probably has *at least* that much chlorine.
Maddie

 

[CrystalRiver]

You say your FC is 0.5, right? That *is* basically ZERO chlorine. Your tap water probably has *at least* that much chlorine.
Maddie

I believe it's required to be 1-4 for city drinking water. 0.5 is too low to be permissible (not safe to drink).

 

[KurtsPool]

Yeah, my chlorine was basically zero but there is algae.

 

[mknauss]

If you are absolutely sure you have no sewer cleanout, then I would suggest you dump to the street. Unless your municipality comes to your backyard they will never know the effluent has algae in it.

 

[KurtsPool]

I believe it's required to be 1-4 for city drinking water. 0.5 is too low to be permissible (not safe to drink).

City's website says 0.5 - 1, this is good info as I was assuming it was 0.

 

[KurtsPool]

If you are absolutely sure you have no sewer cleanout, then I would suggest you dump to the street. Unless your municipality comes to your backyard they will never know the effluent has algae in it.

Will do!