First SLAM- chlorine really jumped

[HeatherH]

Hello all,
I have been dealing with an algae issue for over a year. Anytime I shock, it doesn’t matter how much chlorine is already in the pool, I get what I assume is dead algae. I have always had crystal clear water and normal CC levels but something keeps eating my chlorine (SWG). I finally gave in and decided to SLAM. My CYL is currently 50 so it says SLAM level is 20. This afternoon I was at 13.5 FC. I used the calculator and it told me to add 1 pound and 10 ounces of Cal Hypo. I used two bags because I didn’t want to open my bleach yet. I tested a couple hours after because we got a big rainstorm. The FC was 27. Should it have gone up that much from just two bags of 54% cal hypo? Could I have possibly done the test in some strange was because the shock was so high?

I’m completely exasperated by this stupid dead algae. Everytime I think it’s gone, there it is again. I’m attaching a picture so someone can confirm that this is dead algae. It’s like sand colored and poofs away when you get near it. Thanks for your help!

 

[Texas Splash]

Remember that the SLAM Process takes time. It's not a one-time shock like you did previously. Follow the SLAM Process page carefully and you should do fine. Don't worry about the elevated FC level, it may have been the amount you put in or the figures you entered into the PoolMath APP, but it will fall soon. Watch how the numbers work out next time you calculate your next dosage.

 

[mknauss]

Two pounds of that cal hypo would add 7.4 ppm FC.

 

[HeatherH]

Hello,
In the process of doing my first SLAM. For the last two nights, I’ve passed the OCT and the CC was either at or below .5 this morning plus my water has always been crystal clear. However, I kept testing today and my chlorine went from 22 at 10 am to 16 at 4 pm. My CYA is 50 and we have a sand filter. I stopped bothering to vacuum to waste because I was blowing through too much water. What gives? I had a similar loss during the previous day also.

My frustration level is through the roof with this pool. I’m about to give up on SLAM, permenantly turn off the SWG (it’s off now during SLAM) and just live with the dead sandy algae after I shock every couple days. I’m blowing through way more shock doing it this way and nothing I do seems to fix the issue.

 

[Tcadwall0]

Well, CYA at 50 is ok for a SLAM - but if you are passing all three criteria, then you might need to bring your CYA back up to 70 or so. You are going to have FC consumption during hot sunny days. That is why the OCLT is about overnight, not through the day.

But when you talk about blowing through shock, it also makes me wonder if you are using liquid chlorine?

I just noticed that you had already started another thread a couple days ago. You have responses there, why are you starting another thread instead of continuing that one. It might help people to see the history in one place.

Are you sure it is dead algae? Not other debris from wind, pollen, etc?

 

[HeatherH]

Well, CYA at 50 is ok for a SLAM - but if you are passing all three criteria, then you might need to bring your CYA back up to 70 or so. You are going to have FC consumption during hot sunny days. That is why the OCLT is about overnight, not through the day.

But when you talk about blowing through shock, it also makes me wonder if you are using liquid chlorine?

I just noticed that you had already started another thread a couple days ago. You have responses there, why are you starting another thread instead of continuing that one. It might help people to see the history in one place.

Are you sure it is dead algae? Not other debris from wind, pollen, etc?

I honestly didn’t think to continue the other thread. I suppose that would have made more sense. I was using cal-hypo and then I switched over to bleach today. No, I’m not sure it’s dead algae, but it really only seems to show up after I shock, so I can’t imagine it could be anything else.

 

[Mdragger88]

Heather,
Please understand, the SLAM Process isn’t generally an overnight success.
It takes however long it takes. Usually several days or longer depending upon the condition of the pool at the start. The more often u test & dose to replenish fc to slam level for your cya the faster it will go.
Using cal hypo is expensive. It also adds calcium that only gets removed by exchanging water. Too much ch can cause scaling of your surfaces & swg.
Even though liquid chlorine prices have increased it is still the most efficient with the least unintended side effects.
Look for a source of 10% liquid chlorine/chlorinating liquid/sodium hypochlorite. It’s unadulterated (lots of household bleach now has additives). Walmart, lowes, Home Depot, menards, & ace carry it in their pool section. Also some pool stores offer 10% or stronger in refillable jugs. One near me has this & it comes out cheaper than Walmart.
I see that 13 days ago your cya was at 70 but now it’s 50 - u mentioned vacuuming to waste but that’s still quite a difference.
If the dot disappeared anywhere between 50 & 60 you round up & call it 60. Always round up if in between. This will ensure u are covered with your fc level.

For a successful SLAM Process you need to continue to MAINTAIN Slam level fc for your cya until you meet ALL 3 end of slam criteria-

You are done when:

CC is 0.5 or lower;
You pass an Overnight Chlorine Loss Test
AND
the water is clear.
(Crystal Clear w/no algae dead or alive)

*Check & scrub every nook & cranny where it may hide (light niches, drain covers, ladder handrails, skimmer throats/weirs, etc.)
*Run slam level water through all water features & lines for at least a couple hours a day during the SLAM Process.
*Brush & or vac daily (this breaks up biofilms that algae uses to protect itself from chlorine)
*Backwash/clean filter when pressure rises 25%over clean pressure.
Hopefully these tips help -
Stick with it & then maintain proper fc levels thereafter & u should never need to shock/slam again
Once u are done with slam we can help u sort out your swg woes.

 

[HeatherH]

Thanks for the advice on liquid chlorine. I didn’t know there was a big price difference. I’ll definitely look into the liquid rather than cal-hypo. My CYA was 70 and we did a lot of vacuum to waste and refilling/rain. I will do the CYA again in the morning to make sure I didn’t get the number wrong. I definitely didn’t know crystal clear meant nothing on the bottom, so thank you to clarifying that for me! I’ll try my best to keep going.

Question- my daughter has a pool birthday party (of course!) on Saturday. How high is too high a chlorine level for tiny humans to swim?

 

[mknauss]

How high is too high a chlorine level for tiny humans to swim?

You can safely swim in a pool as long as the FC is above the minimum and at or below SLAM level based on your CYA. You must also be able to see the bottom of the pool in the deep end of the pool.

 

[HeatherH]

Thanks! So I just did my CYA and it’s between 30-40. What the heck? Why did it drop so rapidly?

 

[mknauss]

It is dark in Virginia is it not?
The CYA test should be done in bright sunshine, back to the sun.

 

[HeatherH]

It is dark in Virginia is it not?
The CYA test should be done in bright sunshine, back to the sun.

I did it inside in my kitchen.

 

[Texas Splash]

I did it inside in my kitchen.

CYA Testing:
Proper lighting is critical for the CYA test, so you want to test for CYA outside on a bright sunny day. Use the mixing bottle to gently mix the required amounts of pool water and R-0013 reagent, let sit for 30 seconds, hen gently mix again. Recommend standing outside with your back to the sun and the view tube in the shade of your body at waist level. Then, begin squirting the mixed solution into the skinny tube. Watch the black dot until it completely disappears. Once it disappears, record the CYA reading. To help the eyes and prevent staring at the dot, some people find it better to pour & view in stages. Pour some solution into the viewing tube, look away, then look back again for the dot. Repeat as necessary until you feel the dot is gone. After the first CYA test, you can pour the mixed solution from the skinny view tube back to the mixing bottle, gently shake, and do the same test a second, third, or fourth time to instill consistency in your technique, become more comfortable with the testing, and validate your own CYA reading. Finally, if you still doubt your own reading, have a friend do the test with you and compare results.

 

[Bperry]

Thanks! So I just did my CYA and it’s between 30-40. What the heck? Why did it drop so rapidly?

If you’ve been vacuuming to waste, that’ll do it. Also adding lots of calcium can cause a bit of cloudiness. Don’t use cal-hypo anymore.

 

[HeatherH]

Thanks! So I just did my CYA and it’s between 30-40. What the heck? Why did it drop so rapidly?

Two pounds of that cal hypo would add 7.4 ppm FC.

Ok so I think we are so close to being done slamming. Just a small amount of brown dust this morning. I brought my CYA back up to 70. I do seem to get MORE brown dust when I throw in a bag of cal-hypo than when I use bleach or liquid chlorine. Why might that be?

Here is a new question: How do I determine the gallon size of my pool. We moved into the house with the pool already here and the owner didn’t leave any info on it. I went to a local pool store where he apparently set up an account. The account says 17000 which is what I have been going off of. The pool math calc told me to add 3lb 9 oz of CYA to take it from 50 to 70. I added half of that because I had a gut feeling it would too much. The half took me exactly to 70. So is it possible that I’ve been using the wrong size pool? Would that account for the chlorine going up a lot more than the calc says when I shock?

 

[mknauss]

If you raised your CYA to 70, your SLAM level FC is now 28 ppm. Not a good idea to raise the CYA during the SLAM Process

Be sure to meet all THREE criteria for a successful SLAM.

How did you get your pool volume?

 

[Bperry]

Ok so I think we are so close to being done slamming. Just a small amount of brown dust this morning. I brought my CYA back up to 70. I do seem to get MORE brown dust when I throw in a bag of cal-hypo than when I use bleach or liquid chlorine. Why might that be?

Here is a new question: How do I determine the gallon size of my pool. We moved into the house with the pool already here and the owner didn’t leave any info on it. I went to a local pool store where he apparently set up an account. The account says 17000 which is what I have been going off of. The pool math calc told me to add 3lb 9 oz of CYA to take it from 50 to 70. I added half of that because I had a gut feeling it would too much. The half took me exactly to 70. So is it possible that I’ve been using the wrong size pool? Would that account for the chlorine going up a lot more than the calc says when I shock?

CYA is the least accurate test so don’t discount the pool store estimate with only that. If you’ve been slamming, FC is also not a great way since it can degrade or not very quickly depending on what’s in the water.