FC and CYA levels

[Nickpooch]

Hey guys I have a quick question. I posted a thread yesterday on replacing my water to lower CYA and I believe I did so. It was at roughly 100 and I believe I got it down to 60. Anyway, here’s my question.

I just begun the SLAM process. Just prior to testing I based my FC off of a CYA of 70( I figured I’d go higher just in case my reading was off. Prior to adding liquid chlorine my FC was 6. Using the calculator I added 7 Gallons of Liquid chlorine (10%). I figured I would shoot high once again and let the FC drift lower rather than not putting enough in.

Finally here is my question. I just tested post adding the chlorine and my FC level is 38.5. Wouldn’t this mean my CYA is actually lower than 70 or even 60. I think by adding 7 gallons of 10% with an FC of 6 to a 28K gallon pool wouldn’t raise it to 38.5?

 

[mknauss]

How much the liquid chlorine will raise the FC in your pool has no relationship to how much CYA is in your water.

If your FC went up more than you expected, it is due to your pool volume being less than you thought or the LC % being higher than 10%.

 

[JodieM]

How are you testing your FC and CYA, it says you have test strips.

Your math is correct, adding 7 gal of 10% should raise FC to 25 from 0. Your target slam number is 24. Maybe there was some chlorine in the pool water when you started?

 

[Donldson]

Are you positive the bottle was 10% ? That sounds more like what you would get with 12.5%. If it is definitely 10%, is there a date code? Chlorine is typically sent out stronger than labeled so it remains near the label strength longer, so if it is extremely fresh (quite possible with the current run on chlorine) it could be closer to 12%.

 

[Nickpooch]

How are you testing your FC and CYA, it says you have test strips.

Your math is correct, adding 7 gal of 10% should raise FC to 25 from 0. Your target slam number is 24. Maybe there was some chlorine in the pool water when you started?

How are you testing your FC and CYA, it says you have test strips.

Your math is correct, adding 7 gal of 10% should raise FC to 25 from 0. Your target slam number is 24. Maybe there was some chlorine in the pool water when you started?

I’m using the taylor test kit. My FC was 6 prior. I guess it’s a possibility my pool is less than 28K gallons but the people who put in my liner told me that. Or the liquid chlorine is stronger than advertised. Anyway, since I am about 10 PPM higher than where I should be according to the slam method should I just let it naturally go down and maybe check oclt test tomorrow?

 

[Nickpooch]

Are you positive the bottle was 10% ? That sounds more like what you would get with 12.5%. If it is definitely 10%, is there a date code? Chlorine is typically sent out stronger than labeled so it remains near the label strength longer, so if it is extremely fresh (quite possible with the current run on chlorine) it could be closer to 12%.

Used this

 

[JodieM]

is your water crystal clear now and no debris in the water? If yes, is your cc .05 or less? If yes to both, Then do the OCLT.

 

[Nickpooch]

is your water crystal clear now and no debris in the water? If yes, is your cc .05 or less? If yes to both, Then do the OCLT.

Water is blue but cloudy. Can’t see bottom at all. This is why I slammed in first place. CC is .5. In the meantime after I added chlorine I scrubbed walls and floor a lot. Robot vaccum got a lot of debris and leaves off bottom. Can’t vaccum to waste as I can’t see bottom. Added DE to sand filter to hopefully speed up. What else should I do

 

[Nickpooch]

Will I see big difference after getting FC that high? What is reasoning for cloudiness? Old algae?

 

[mknauss]

Follow the SLAM Process
Read the article.

 

[Nickpooch]

Here are stats for 28K vinyl pool.

FC:38.5 (same aslast Night)
CC- .5
TA: 70
PH: 7.2 (tested prior to adding chlorine )
Hardness: 150

Pool is blue but murky. Can’t even see bottom of shallow end. At what point do I chalk this up to a filter issue. I have a sand filter and the pressure seems to be holding at around 16 PSI. I’ve added DE to try to aid the filter. What else can I do? My robot vaccum has been getting pounds of leaves and sand off bottom. Tough to vaccum because I can’t see.

 

[Nickpooch]

CYA is 60-70. Tough to tell. My eyes suck

 

[Texas Splash]

What else can I do?

At this point, be patient. Deep breath. The SLAM Process is reliable and works, but it's not a quick fix-all either. If we use the higher CYA of 70, then an FC of about 28 is as high as you need to go. Increasing over that doesn't help the SLAM go any faster. Continue with all the SLAM recommendations of brushing, sweeping, vacuuming, backwashing, etc, and allow the chlorine and filter the time they need to help your water recover. Your water clarity should improve slowly each day. If not better in the next day or two, let us know.

 

[JoeSelf]

Don't do OCLT unit you have passed ALL three criteria. Water will look like GIN when you are ready.

 

[Nickpooch]

Hey guys I’m in night 2 of the slam. Stats below for 28K pool. I live in NJ and it was only 45 degree today

FC: 28 (dropped from 38.5 in 7 hours)
CC-.5
CYA-60-70(SLAM off of 70)
PH- 7.2
I’m wondering what would cause my FC to drop by that much. I do still believe I have a lot of leaves at the bottom that the vaccum keeps picking up..could that be it? I’ve been scrubbing the walls in case of algae as well. Does that seem like a quick drop? I added 2 more gallons of 10% bleach which should bring my FC closer to 35 (I don’t want it to drop below SLAM level over night )

My robot is getting a ton of leaves and sand, i just want to make sure I’m doing everything right.

 

[mknauss]

Please do not raise your FC so high above SLAM level. You are not doing your vinyl liner any favors.

Test at least three times per day and raise your FC back to SLAM level FC - 28 ppm for your CYA.

 

[Nickpooch]

Update:
Pool looks the same. Blue but extremely cloudy can’t even see beyond 1 foot in shallow end. Not sure if it’s a filter issue. SLAM doesn’t seem to be working.

Just tested: 28G pool

FC-28
CYA- 65-70
PH 7.2
CC- .5

 

[mknauss]

You are in day 3. Patience. A sand filter takes the longest to clear a pool during a SLAM.

 

[Nickpooch]

Updated pics. Pool still looking very cloudy. Can’t see bottom.

 

[Texas Splash]

Yeah, but you are getting close. Maintain! You'll look at the water one one morning and say .... "There it is!" You'll get there.