Clear water BUT continual chlorine loss

[SherryRae]

Hello all 

I have referred to this site often and those special guys that have all the answers (you know who you are!)  I have learned a lot and have been using the dichlor transition to bleach method overlayed onto a swg tub.

My current situation has me perplexed though.  Water is clear but chlorine continues to be 'eaten' and the swg doesn't seem to be producing.   Not sure why this would be and don't know if I am missing something??

I will try to provide info I think you would ask for.  Just a couple days ago I did a shock with 2cup bleach because of the scenario I have described of clear water but constant chlorine loss.  I thought this solved everything as it popped the chlorine up and I had a residual the next day.  At this point I thought whatever was eating the chlorine that was invisible (ie no cloudy water?) had been eradicated and that the swg would take over from there.  BUT, today chlorine is back to less than .2 (fc of course)... cc is .4.

So I'm not sure how to proceed.  Prior to the shock I was just adding a little bleach each day to maintain the fc.

So ph is @ 7.4

Cya a little high at 80 (this is taylor test.. this is approx as I'm always a bit unsure when the black dot actually disappears!)

Salt is @ 1750.. that is before I added this most recent 2c bleach

Tub size is 340g

And I recently replaced the swg cartridge 

Thanks for any suggestions

SherryRae

[RDspaguy]

3 hours ago, SherryRae said:

you know who you are!

@waterbear, this must mean you.😉

[waterbear]

On 1/24/2021 at 1:26 PM, SherryRae said:

chlorine is back to less than .2 (fc of course)... cc is .4.

Taylor K-2006 and 25 ml water sample?

On 1/24/2021 at 1:26 PM, SherryRae said:

Prior to the sIF the Shock I was just adding a little bleach each day to maintain the fc

if the SWCG was working properly you should not have needed to add bleach daily.

On 1/24/2021 at 1:26 PM, SherryRae said:

swg doesn't seem to be producing

That would be my guess.

On 1/24/2021 at 1:26 PM, SherryRae said:

And I recently replaced the swg cartridge 

DId this problem start after you replaced the cartridge or was it before

 

On 1/24/2021 at 1:26 PM, SherryRae said:

Salt is @ 1750.. that is before I added this most recent 2c bleach

Bleach should not have any major impact on salt level. What brand of SWCG do you have and what is the manufacturers recommended salt level? How are you testing the salt level? Are you using a drop test, salt test strips, or a readout on your unit?

[waterbear]

On 1/24/2021 at 5:14 PM, RDspaguy said:

@waterbear, this must mean you.😉

For those old enough to remember:

[SherryRae]

Ok.. sorry for the delay in responding.. I am also dealing with computer issues.. so that has drawn my attention away.. anybody experts in that out here?🤔😛.

Anyway, yes I believe my Taylor kit is the 2006.. I got it from leslie's so it isn't labelled,  but says 'complete (fas-dpd) chlorine.. it has drip test for fc.cc.ph.ta.ch.cya.  unfortunately I didn't not have the salt component.. I just use strips.. I should probably purchase that for better accuracy.   And yes I use 25ml sample.

I do feel the bleach affects the salt level as it is the only addition that could be the reason it goes up?

The swg cell is freshwater brand.

Just so perplexed how water is clear but continues to eat chlorine.. and the cc level isn't high?  Even if the salt cell isn't working, shouldn't the tub be able to retain fc if there is no load and the lid is closed so no sun breakdown?

So on 1/27 I doused it with 3c bleach.. the fc spiked, but was only 14 after 1 1/2hr.. which the 3c according to my calculation should have drove fc initially to 36ppm.  At 9hr out it was down to 6.2.  Today it is .2 or less.. and no one has been in it.  Cc is also .2 or less.  Other values are: pH 7.5, ta 70, cya 90 (I don't know how that got so hi!  I think I must have misread it at some point and thought it was low so added some doses of dichlor), ch 80, salt 2000? (Test strip so limited accuracy).  I also added borax during the startup but I don't have a test for that level.. I added 2 1/2c.

I appreciate any insights.  I am fairly new to this.. have only done 2 total water changes so far.  I am keeping a spreadsheet trying to track these values and my actions and gather load etc to hopefully come up with a plan by seeing how my tub behaves given the factors of our use etc.

I have looked up information here of course, but if anyone has specific links to recommend for a saltwater tub set up and maintenance that would save me search time 😁.

If seeing my spreadsheet would help, I can try to figure out how to link that here.

I think I need to just do a drain and refill, but it is so cold now.  I expected this water to last longer.. the bather load has not been excessive at all

[SherryRae]

some added info... i added 1/2c bleach and 4T mps.. 2hr later fc reads 13.2 and cc .4 ... HOWEVER if i use the mps deox procedure with taylor kit i get---

9.6fc and .8cc??  Now i have sent in a question to them directly because the procedure is diff for the 2 tests.. obviously it is diff since we are adding the deox, but what i mean is that in the std testing situation you test for cc immediately after adding the 0003 reagent, but in the deox situation the instructions say to wait 1 minute.. well that definitely affects it.  So should i be doing this all along in the std testing method too??  it does not state that in the instructions!  

i also don't understand why the deox reagent goes in before testing fc as supposedly it's presence should only affect the cc value?

so sherry is confused

i ran the std test and did the 1min wait for cc.. that made it come out as .6 instead of .4

i also ran the deox test and measured cc w/o 1min wait and if came out as .6 instead of .8

i really don't understand why the deox version of test would register a higher fc??

guys i am sorry for my ignorance!!  i really hate not understanding things.  i am trying to make every effort to understand my maintenance.

also don't see how this last dose raised the fc to that high a level as 1/2c bleach should only provide 6ppm

soooo.. help me if you so choose!

thanks guys

[waterbear]

23 hours ago, SherryRae said:

I am also dealing with computer issues.. so that has drawn my attention away.. anybody experts in that out here?

Actually yes, used to work in IT and was a programmer in the 70s and 80s.

23 hours ago, SherryRae said:

And yes I use 25ml sample.

Use a 10 ml sample, 1 scoop of DPD powder (add additional scoop if the color does not hold because chlorine/MPS levels are high) and then each drop of titrant will equal .5ppm instead of .2 ppm if you don't use MPS. With the MPS interference reagent Taylor only provides instructions for a 25 ml sample although I suspect the test will also work with a 10 ml sample in which case 1 drop of titrant should still be equivalent to .5 ppm of FC, CC, or Total oxidizer.

23 hours ago, SherryRae said:

I didn't not have the salt component.. I just use strips.. I should probably purchase that for better accuracy. 

The Taylor salt test is difficult, to say the least. The AqauChek or Hach salt titrator strips, are fine. Main thing is to remember to let them sit in the sample long enough to get the reading. I have found that it usually takes about 5 minutes or so.

 

On 1/30/2021 at 11:05 AM, SherryRae said:

Even if the salt cell isn't working, shouldn't the tub be able to retain fc if there is no load and the lid is closed so no sun breakdown?

Not necessarily. IF there is no system that is adding chlorine automatically such as a SWCG or some type of feed system such as a peristaltic dosing pump (not normally used in residential chlorine spas) then daily additions of chlorine are often needed to maintain the desired FC level, even with no use.

On 1/30/2021 at 11:05 AM, SherryRae said:

So on 1/27 I doused it with 3c bleach.

3%, 5.35%, or 6% and how fresh was it? (These are the common strength for household bleach and bleach does lose strength if it is old)

On 1/30/2021 at 11:05 AM, SherryRae said:

added borax during the startup but I don't have a test for that level

Get some LaMotte borate test strips. They are much easier to read than the ones from AquaChek, Hach, and Taylor. You will probably need to order then online.

 

On 1/30/2021 at 11:05 AM, SherryRae said:

I do feel the bleach affects the salt level as it is the only addition that could be the reason it goes up?

All forms of additional chlorine will cause salt to rise but it is not significant unless you are not doing water changes. What color is the salt indicator/system status on your system (red or yellow) and is it on the left, center, or right? what status message is displayed on the panel.

 

On 1/30/2021 at 11:05 AM, SherryRae said:

If seeing my spreadsheet would help, I can try to figure out how to link that here.

Not really, IMHO, since the status of your spa will change with such factors as the usage, temperature, time since last water change, age of salt cell, chemicals used and changing water parameters. I prefer to work from a current set of test results to troubleshoot problems, Older test readings are not really relevant to what is happening right now in your spa.

[waterbear]

20 hours ago, SherryRae said:

fc reads 13.2 and cc .4 ... HOWEVER if i use the mps deox procedure with taylor kit i get---

9.6fc and .8cc?? 

IF there is MPS present you need to follow the procedure in the MPS interference remover add on. The standard testing method does not give correct results.

20 hours ago, SherryRae said:

So should i be doing this all along in the std testing method too??

IF you have MPS in the water you should not be doing the standard testing. Period. You need to follow the instructions to  remove the interference. It's that simple.

 

20 hours ago, SherryRae said:

also don't understand why the deox reagent goes in before testing fc as supposedly it's presence should only affect the cc value?

because you have to removed the MPS before testing for CC which is done on the SAME sample when you add the R0003 (potassium iodide), which converts both MPS (if present) and CC to Iodine compounds which are measured by the DPD titration. Also, if you wait the MPS will start to register on the FC test, which is why the deox reagent needs to be  added IMMEDIATELY (Similar to the way an OTO test will intially read FC if read in the first few seconds then will read TC as the CC reacts with the reagent more slowly)  IF the MPS is not removed from the sample then you will be testing for Total Oxidizer (the third test on a NEW sample that does not have the deox reagent nor is the FC neutralized by an initial titration before adding R0003). In a non MPS situatiion the first titation removed FC from the sample which then has potassium iodide added to convert the remaining CC to iodine compounds that DPD will react with, which is why the clear sample turns pink again when you add the R0003. IF MPS is present it will also oxidize the iodide to compounds that the DPD will react with, giving a false reading.

 

21 hours ago, SherryRae said:

really don't understand why the deox version of test would register a higher fc??

guys i am sorry for my ignorance!!  i really hate not understanding things.  i am trying to make every effort to understand my maintenance.

also don't see how this last dose raised the fc to that high a level as 1/2c bleach should only provide 6ppm

My guess would be testing error. It happens. Variations in drop size, miscounting, variations in sample size, not adding the deox reagent quickly enough, etc. can also cause testing errors.

Bottom line, you are using MPS so you need to follow the procedure for MPS interference. PERIOD. If you decide not to use MPS after a drain and refill then you can go to the 'standard' testing procedure and I would recommend a 10 ml sample so each drop of titrant is eqaivalent to .5 ppm of free or comined chlorine.

[SherryRae]

So I haven't used mps until this most recent chemical addition.  I assume it remains.. doesn't decay after a period of time?.. so if I use it I should do the detox indefinitely?  And what is your interpretation of the Taylor instructions requiring a 1 minute wait to test cc when using the deox but not with the std testing?  That perplexes me why there is a diff in procedure?  And obviously affects the result. 

Do you use mps?  If not, what do you use as periodic 'boost' to remove oils etc?  And do you apply enzyme at times?

The bleach is 7%.

The display is currently reading yellow to the right (3o'clock) but says 'salt system ok'

Test values just now.. 28hrs later = fc 3.8 (deox) 4 (w/o)  cc .8 (deox) .4 (w/o & no wait) .6 (w/o & wait)

So can water look crystal clear but still have issues?  Everything I have read seems to imply problem would be signaled by cloudy water etc. 

And I like using the 25ml since I would think it would provide more accuracy since increments are .2?

And refusing my spreadsheet??  If you knew all the fields of info I collected you may feel differently! 😊.

And you probably shouldn't have divulged that you are a computer geek.. a different kind of nagging may begin...