Shocking pool with Biguanide

[vatdye]

I've been caring for a pool using the dichlorotriazine etc. system for 6 years without problems.
The man opening the pool this year is shocking with biguanide which I am not familiar with. He has been at it for about 9 days and is now adding chlorine ( dichlor, trichlor, hypochlorite, calciumhypocholorate) and circulating thru filter. The pool has been unattended for 1 to 2 days.
I checked with Cl and biguanide test strips today:
Cl - 1ppm
pH - <6.2
Alk - 40ppm
Stab. - 0
biguanide - 15ppm
He is going to hand over the pool ready for the dichlor system.
I'm concerned about the low pH and Alk levels and the time required for this preparation.
He is also running the the operation with the water level 3-4 in. above the skimmer intakes. The pool water appears blue but is very milky/opaque.
Does this look normal to you? Should I be concerned?

 

[JasonLion]

Welcome to TFP!

If you have your facts right, that is insane. You should NEVER add Biguanide to a chlorine pool. Aside from being a significantly inferior disinfectant, and being way more work than other approaches, it leaves globs of residue that tend to destroy your filter media when you switch back to chlorine.

Now if he has been adding bromine I could maybe understand. But if it is really Biguanide, fire him now and keep him away from your pool.

Oh, I forgot to mention that having the PH that low is damaging the pool.

 

[vatdye]

The pool had been standing over the winter and was full of algae so it contained no Cl. The sin was adding Cl compounds after using biguanide or baqua-cide. If he kept Cl at 1ppm and biguanide at 15 ppm would that still creat the problems you mentioned? Would bromine regester the same on chlorine test strips as chlorine?
We have a filter with DE on cloth frames. Are the biguanadine residues going to plug up the cloth?
Many thanks for such imformative and fast responce, vatdye

 

[chem geek]

Chlorine and biguanide are incompatible chemicals no matter what their level. Bromine measures in chlorine tests, but why are you asking about that? Bromine is not the same as biguanide. Chlorine will react with biguanide (and vice versa) to form a chemical mess and yes it will get caught in your filter and possibly be very hard to clean, though perhaps if the chlorine level was very low you might not have a big reaction. The downside is that if he really did add a lot of biguanide, then that's what you now have for sanitation in the pool. If you want to convert back to chlorine, you can, but it's not a trivial process -- many have done it on this site.

 

[vatdye]

I asked about bromine because Jason suggested that bromine might be O K and at that time, I was getting a positive test for 1 ppm chlorine on test paper.

I agree. The guy working on the pool must go. He refuses to answer phone or e-mail so I can only tell you what I see.

The pool has been recycling thru the filter for about 10 days. The water currently shows 15 pmm on biguanides test paper but there is now no detectable chlorine (Cl test paper). Could Jason's "Convert your Baqua pool to Chlorine" procees be used to remove the residual biguanides?

On slime, I cannot feel or see it in pool but I have not seen the inside of the DE/cloth filter - will have it opened soon. The filter pressure has been running at 15 PSI for days. Does this indicate absence of serious slime problem?

Water is green/opaque and appears to be slowly clearing up.

I worked for 35 years in R&D for some large manufactures of dyestuffs. I'm 86 and a bit rusty. We also used hypochlorite purifications on some of our products. I have also run this pool using the chloro-s-triazinetrione system for 6 years without any problems. I did not hire the pool man nor was I aware that he was going to use the biguanides process.

Thanks for the help. vatdye

 

[chem geek]

Could Jason's "Convert your Baqua pool to Chlorine" procees be used to remove the residual biguanides?

On slime, I cannot feel or see it in pool but I have not seen the inside of the DE/cloth filter - will have it opened soon. The filter pressure has been running at 15 PSI for days. Does this indicate absence of serious slime problem?
:
I have also run this pool using the chloro-s-triazinetrione system for 6 years without any problems.

Yes, you can bring your pool back to a chlorine pool by following that process, though it will go much more quickly because there probably isn't much biguanide he put in (I hope -- maybe there is in which case you're in for some interesting colors in the water).

It doesn't sound like you've got a serious slime problem. A better way to tell will be when you convert your pool to chlorine and do an overnight chlorine loss test.

The chloro-s-triazinetrione, aka Trichlor assuming you were using tabs/pucks (you mentioned dichlorotriazine in your first post, but that's granular/powder), builds up CYA over time so you just got lucky or otherwise managed to keep your CYA in check or your FC high enough. Most likely, your pool was poor in algae nutrients and you had some water dilution (assuming you weren't using any algaecide).

 

[vatdye]

The water is now clear and 15 ppm FC was maintained for most of today.
We finally reached our ex - pool man for questions and he maintains that he only used Cl for shocking. Before this, the only evidence we had that biguanide was involved was my positive test on biguanide test paper. Could this have been a false positive? If so, all this is my fault and I appologize. Is there a more definitive test for biguanide?
Thanks again. vatdye

 

[Richard320]

The water is now clear and 15 ppm FC was maintained for most of today.
We finally reached our ex - pool man for questions and he maintains that he only used Cl for shocking. Before this, the only evidence we had that biguanide was involved was my positive test on biguanide test paper. Could this have been a false positive? If so, all this is my fault and I appologize. Is there a more definitive test for biguanide?
Thanks again. vatdye

It would look something like this when you add bleach.