Free Chlorine problem

[Seadog]

tds: 3500
cya: 25
tot chlorine: 10
free Chlorine: 0 <===== the problem
ph: 7.6
tot alkalinity: 327
adj. total Alkalinity: 319
tot hardness: 356

[mwsmith2]

Those results look REALLY suspect to me, like they were generated by a computer reading a test strip. They really don't make much sense. I don't know of any drops-based test that measures down to individual units for alk and Ca. I'd go have your water tested elsewhere. Basically it's telling you have CC of 10 which is really, really high. Seeing alkalinity and Ca matching up so close is kinda weird too. It's easy to solve the CC problem though, just dump in bleach to bring your Cl up to 15 or so and hold it there until the CC reads down to 0.

Michael

[waterbear]

I would suggest you get a good drop based test kit and test your own water. It is possible that the pool store is making an error in the testing. (ya' think?) According to Talor Technolgies who manufacture one of the better drop based test kits chlorine levels > approx. 10 ppm can "bleach out" a DPD test for chlorine! You might want to try a different pool store and compare the results. Or ask your pool store to do a dilution on the sample before they test for this reason if they are using DPD. Does your water have a strong "chlorine smell"? This would be an indication that there is combined chlorine in your pool. With no FC and 10 ppm CC (CC=TC-FC) it would mean that all the chlorine in your pool is combined.

Also, do you use a non-chlorine shock? Monopersulfate can also cause interference with DPD testing and show an elevated level of Total Chlorine!
If this is the case it is possible that your chlorine levels are very low and only the shock is showing up on the testing. Taylor Technologies also sells a reagent to help remove this interference.

IMHO, the 2 most probabable scenarios are: either you have very high chorine levels and the type of testing being done is giving inaccurate results because the pool store is using DPD and not FAS-DPD testing (or diluting the sample and DPD testing) and it is bleaching out
or you have an incredible chlorine demand problem and all your chlorine is converting to combined chlorine and you need to shock.

Until you determine which it is you really can't know what you need to do.
Since you just opend the pool it is possible that the chlorine demand is high right now.

Test strips that use syringaldazine reagent supposedly don't "bleach out" (don't know if this is acutally true but that is what is said about them) so if test strips are showing no FC it is possible that the chlorine demand is high

Sorry I can't give you a more definative answer but without GOOD test results from a PROPERLY DONE drop based test it is next to impossible.

[Seadog]

thanks, I watched them test it and it was some sort of machine that they put the water into, wasn't a test strip. no strong chlorine smell.

Thanks for all your help.

[mwsmith2]

Yeah, then those results are junk. Get it retested somewhere that actually uses test reagents.

Michael

[CarlD]

There are two ways to use strips:

1a) Dip the strip and look at the FC/Free Chlorine side. If it's white, I
have a problem. If it's deep purple, I'm probablly OK. Anything in
between I test with something ELSE that's more accurate.
b) Ignore ALL the other tests on the strip--they are totally worthless
because they are extremely inaccurate.

2) Don't use test strips.