Can combined & free chlorine go up if no diclor or chlorine or bleach is added?

[duganderson]

I have a 400 g. hot tub and measure FC and CC with a Taylor k-2006 kit with MPS correction regent R-0867 AND a Hach strip.

Both Taylor k-2006 kit with MPS correction regent and Hach strip show increases in CC from 2.0 PPM to 4.6 AND FC from 1 to 1.8 in the past few days but I have NOT added dichlor, chlorine or bleach. I've only added PH down, Alkalinity UP and MPS. Should any of these INCREASE the FC and CC?

I use Nature2, MPS after every soak (daily) and weekly addition of 1 cup bleach (my CYA is 100). I used to use 2.4 T. diclor weekly.

Thanks, Doug

 

[jimmythegreek]

I beleive mps will raise your #s. Is CYA 100 on purpose or the results of sanitizing with shock?

 

[duganderson]

I beleive mps will raise your #s. Is CYA 100 on purpose or the results of sanitizing with shock?

No, the CYA is from Diclor. I'm planning to reduce CYA by doing a partial water change. It was just -20 F yesterday so water changes are on hold for a bit.

 

[JamesW]

Do you have ozone?

Have you ever added bromine or sodium bromide?

 

[duganderson]

I do not have ozone and have not used bromine or sodium bromide.

 

[duganderson]

I've drained and filled my 400 G. hot tub twice. Both times it needed about 12 OZ sodium bisulfate to bring down the Alk & PH. When I do a drain and fill, can I add that entire amount (12 OZ) at one time? Any tips?

 

[mknauss]

No. Adjust your pH to no lower than 7.2, aerate until it is 7.8 or higher, then repeat until your TA lowers. Adding all the acid at one time can destroy metal (heating element).
Also, you would be better off to use muriatic acid. The Dry Acid adds sulfates, which also destroy your heating element over time.

 

[jseyfert3]

Both Taylor k-2006 kit with MPS correction regent and Hach strip show increases in CC from 2.0 PPM to 4.6 AND FC from 1 to 1.8 in the past few days but I have NOT added dichlor, chlorine or bleach. I've only added PH down, Alkalinity UP and MPS. Should any of these INCREASE the FC and CC?

No, none of those will increase FC or CC.

Not sure why the values increased. MPS obviously affects the test but that’s what the MPS interference remover reagent is for. Are you doing the test quickly and following the instructions closely? I remember reading the MPS instructions and the emphasis on IMMEDIATELY adding the MPS reagent.

If you’re adding both alkalinity increased and pH minus you’re fighting yourself, pH rise is faster with higher TA. Let the TA drop lower and the pH rise will slow.

No, the CYA is from Diclor. I'm planning to reduce CYA by doing a partial water change. It was just -20 F yesterday so water changes are on hold for a bit.

Some CYA is good, but once you have that (30 ppm) there’s no need to add more until what you have breaks down from chlorine and heat. In other words there’s no reason to add both dichlor and liquid chlorine, you can do liquid chlorine only once you’ve used dichlor (or straight CYA) to get a base level of CYA established.

 

[duganderson]

[B]jseyfert3[/B].....thanks for your responses.

Yes, I'm following the chlorine directions closely. It almost seems like the chlorine regent is bad. My test strips seem to reflect reality but the Taylor seems off. The rest of my Taylor 2006 seem to be accurate.

I stop using diclor once I get to 30 CYA and then switch to bleach as recommended in this forum.

[B]mknauss[/B]......Thanks for your response. That process worked great for lower Alk and Ph.

 

[proavia]

[B]jseyfert3[/B].....thanks for your responses.

Yes, I'm following the chlorine directions closely. It almost seems like the chlorine regent is bad. My test strips seem to reflect reality but the Taylor seems off. The rest of my Taylor 2006 seem to be accurate.

I stop using diclor once I get to 30 CYA and then switch to bleach as recommended in this forum.

[B]mknauss[/B]......Thanks for your response. That process worked great for lower Alk and Ph.

@duganderson
I would believe the K2006 results 100,000 times before I believed a test strip 1 time.
They aren't referred to as "guess strips" here for no reason.
As long as your reagents are not expired and the test kit has been stored indoors, believe its results.

 

[duganderson]

I just drained about 75% of the water (I"m in MN and it was WAY too cold to do a total drain). I added a cup of 8% bleach after balancing the water but now the combined chlorine is about 8.0 PPM and we have not used the tub since the 75% water change. What do you think is going on? Do you think I have bio film in the lines? I'm done 3 flushes with the previous two drains and refills.