Burning through Chlorine..> no usual suspects

[dunginhawk]

Good day all. So Ive been around the pool and tub forums a little over a year.. Had my ups and downs.
early on I had a similar hot tub issue with chlorine just going away FAST.
Ive learned
1. Make sure SWG is operational and salt level adequate.
2. CYA - without CYA chlorine goes hyper fast
3. PH - a pH over 8 and it goes fast too.

However, right now, NONE of these are the case. CYA is 50+ PH is 7.5 and Salt is 3k, right where ive always kept it. Even if the swg isnt working, there is NO WAY i should be using this much chlorine.

For instance... I found my 12.5% to be 1/3 as useful, because its about 8 months old.. ok, so 3x the amount.. fine.
My tub had about 1-1.5 FC last night before bed. I put in 12 oz of 12.5% chlorine (remember its only 1/3 as useful) Just tested it now (12 hours later or so) and its at 2FC.
If I add another 12 oz, by tomorrow, its down to 1-2 again.
Just no idea why this is happening. Could there be that much bacteria in there? Ive never let this water change hit 0 FC at all.
Just puzzling to say the least.

 

[ajw22]

Do a Overnight Chlorine Loss Test. If you are losing FC at night then you have algae in the water even if the water looks clear. Follow the SLAM Process step by step with no shortcuts.

Post a complete set of test results...
FC
CC
pH
TA
CH
Salt
Water Temp

 

[dunginhawk]

I have done an overnight loss test each of the last 2 weeks haha. Its like 10FC at least.
I will have to figure out exactly how effective this chlorine is first, so I am adding the right amount.

 

[ajw22]

Stock up on R-871 and then just keep on adding chlorine, wait 15 minutes, test the FC, and repeat until you reach your SLAM FC level. You will learn after a few tests how many ozs raise your chlorine how many ppm.

 

[ant 83]

another thing not mentioned is temp.

If you run the tub hotter in the winter, it will use a noticeably larger amout of chlorine.

 

[dunginhawk]

Yep.. totally get that too... its just WAYYYY too much.
ANyway, this morning I went out and did the math... with my 12.5% chlorine jug 4oz = 3.2 or so FC>.. So with that said, and the CYA im running, I upped it to 20 FC and its running there now.
Ill check it in 30 minutes, and add as necessary... slam under way

 

[dunginhawk]

30 minutes later, down to 15 FC from 20. BUmped back to 20... 30 minutes later, down to 17... waitingggggg

 

[dunginhawk]

45 minutes later.. down to 16-17 again...chlorine is munching on something. good lord

 

[dunginhawk]

Didnt get to it for a few hours... down to 14 FC. Bumped it back to 20, will check in the morning.. Man thats a lot of chlorine loss

 

[jseyfert3]

I see you have an ozone system, and I don't remember people asking about it in your previous thread. Is this turned off? UV and/or ozone will distroy FC, so they must be off (along with the SWCG) to get an accurate FC loss test.

 

[dunginhawk]

I cant turn them off... they are hard wired.. id have to pull the panels,get in to the power unit etc.
Ive had this tub for 1.5 years, and never had an issue with the ozone hurting... Im going off 1.5 years of history and this is 10x the normal burn rate... so ill stick with the slam and see where it puts me.

Btw it was down to only 14 overnight. thats like 10 hours of time. i was losing that in about 30 minutes yesterday.. so its doing its thing

 

[ant 83]

A couple of years ago my ozone stopped making bubbles. So nice to not have to hear that anymore. Good riddance.

Anyway there are times where it seems like I too, have a "chlorine debt" owed to the tub. Running SLAM protocols is also how I handle it.

I'ts good practice to run CYA, and PH tests after your FC falls, because they are effected by the chlorine additions.

In fact, as long as my PH is higher than 7.8 when I start, I bust up a 3 inch chlorine puck, and add chunk to a spa floater, that's dialed almost closed.

Trichlor is too acidic to use for all chlorine needs, but I find that it works good to use as a slow release acid. The fact that it adds FC/CYA as well is the gravy that led to better water quality for me.

 

[dunginhawk]

So in the last couple hours it appears to be holding at 20FC... the PH has crept up to around 8, so I brought that back down... monitoring

 

[dunginhawk]

Will running that high of FC affect the PH? my ph was pretty much in line when i started this SLAM.
Now its sitting around 8.1/8.2 which can obviously affect the FC for sure. I just put in some more PH down to try to get it in check

 

[jseyfert3]

FC doesn't change pH BUT it messes up the pH test. If the FC is higher than 10 ppm the pH test is invalid, and pH should not be changed until your FC drops below 10 and you can get a valid pH test.

 

[ajw22]

Will running that high of FC affect the PH? my ph was pretty much in line when i started this SLAM.
Now its sitting around 8.1/8.2 which can obviously affect the FC for sure. I just put in some more PH down to try to get it in check

Don't bother checking pH during the SLAM Process. Lower the pH then just check FC and CC.

Read Taylor pH Test is Unreliable When FC >10

 

[dunginhawk]

Thank you... so over the last 6 or so hours it only dropped from 20 to 17.. so i bumped it back up to 20... this is day 3 of this slam.. is this normal? haha

 

[ajw22]

Thank you... so over the last 6 or so hours it only dropped from 20 to 17.. so i bumped it back up to 20... this is day 3 of this slam.. is this normal? haha

Very normal process as chlorine demand drops and then you have a longer tail to get all the algae killed. Keep at it and don't stop until you are able to pass the Overnight Chlorine Loss Test

 

[dunginhawk]

I have a cover on, so the overnight thing is really just a 12 hour thing for me.
I just need to not drop for 12 hours to be good... cant believe its taken this long ha

 

[ajw22]

It takes a while to get it all killed. Algae lingers.