Dichlor/bleach method - cloudy water after adding liquid chlorine

[Jimmie]

I'm experiencing repeatable cloudy water with the dichlor/bleach method.

I have followed Nitro's guide carefully. I understand all the steps and the process. I got my TA down to 54ppm with pH under 7.6. My CH is 264ppm (hard water) and CYA is 37ppm. I have perfectly clear water until the morning after a two-person one hour session in the tub.

After the session I top up the FC with liquid pool chlorine and the next morning it's cloudy with pH risen to 7.9 or beyond.

I expect that the high pH has caused the dissolved calcium to come out of solution making the water cloudy. I put in enough pH minus (dry acid) to lower the pH and it clears in a few hours without filtration.

I've never let my chlorine drop to below 2ppm and my CD is about 29% so I know it isn't due to poor sanitisation.

I haven't added borates (boric acid, borax etc) as it is banned in Europe/UK and only available to professional trades.

I'm pretty sure the liquid chlorine plus the aeration is pushing the pH high enough for the calcium to come out of solution.

Here is a link to the liquid chlorine: 5 LITRE BOTTLE OF LIQUID CHLORINE (lincsproducts.co.uk)

This has happened twice and both time I have recovered with pH minus alone.

I've owned my hot tub for 3 years running dichlor and not had this particular problem before. I've only recently this week tried the switch to dichlor/bleach method.

Any clues what might be going wrong? The liquid chlorine specification looks to be the correct one to me for this method.

[dashmer]

A ph of 7.8 - 8 is typical of tubs running the dichlor then bleach method and it will stay in that range for quite a while before you need to add acid/ph Down. Your TA is on the slightly low side of what is recommended, but if your pH is stable it is probably OK.   I know you mentioned not having borate available, which also helps with the pH stability.

Your CH is on the high side of good, but perhaps not an issue. I will defer that question to one of the forum experts.

What is the % sodium hypochlorite of your pool chlorine, how old is it and how much did you use after your 2 person 1 hour soak?  Also, what are you using to test the water?

[Jimmie]

The thing is the pH was 7.9 or greater the morning after. That's a good 12 hours later.

I use a PoolLab 1.0 digital photometer. PoolLab® 1.0 - Water Treatment Products

The liquid pool chlorine is stated to be 12-15%. I make it to be 10% judging by how much I need to raise by 1ppm and my tub size.

My last session I raised the FC to 10ppm for a weekly shock. That was 105ml or 7 15ml doses (15ml per 1ppm raise). The time before that I only needed to raise it by 4ppm to raise it enough to have more than 2ppm in the morning. On both these occasions the water was cloudy in the morning and pH still high. Adding just pH minus resolved the cloudy water without constant filtering.

[Ahhsomeguy]

Hi Jimmie:  When was the last time you purged biofilms from your hot tub plumbing?  Have you ever performed a purge?  Biofilms can raise havoc with sanitizer tizer demand and create numerous maintenance issues.  Purge the tub with an effective purge chemical.  You may find that yiur issues disappear.

[Jimmie]

Very recent. 26th August. Flushed out with Ahh-soome. Cleaned the shell. Ran pumps briefly to eject water then vacced out the rest. Refilled, shocked. Usual drill. As I said, my CD is 29%.

[Ahhsomeguy]

Jimmie:  When you purged the tub did youmget a very profound release of discoloration and stickies?  

[Jimmie]

It was discoloured and sticky.

[Ahhsomeguy]

Jimmie:  Many times a hot tub requires additional purges to remove most or all of the gunk in the lines.  If you have additional product leftover why not purge again to be sure the majority has been removed?

[dashmer]

I think Jimmie may also want to have someone look into his pH/CH comment.  @waterbear could possibly rule that in or out...  

[Jimmie]

I’m currently running another purge. There is still some yuck coming out. Nowhere near as much as the first time though and far far more foam. Yes I only put 3 teaspoons in. I thought it was going to overflow with foam!

[Ahhsomeguy]

Great.  Let’s get the plumbing clean so when you begin the chemical program we can rule out biofilm issues.  Good man Jimmie.  Glad you purged again.

[Jimmie]

Also this time I intend to stabilise the TA and pH using the slower method over a few days rather than the method in Nitro’s guide.

[Jimmie]

@Ahhsomeguyare you a dichlor only guy or dichlor and bleach guy?

[Ahhsomeguy]

My hot tub is a 720 gallon inground gunite w/marcite finish.  I use tri-chlor 1 inch tablets in a Rainbow feeder for ongoing maintenance along with 3.5 ounces of Aqua Clarity weekly. I use household bleach as a shock treatment usually every 2 weeks or so.  I have had crystal clear water every single day since the hot tub was built, over 7 years now.  I use a test kit utilizing DPD tablets.  Aqua Clarity and chlorine is all every single hot tub needs to use other than periodic pH and TA control.  That’s exactly what I use.  You cannot use Tri-Chlor.  You can use Di-Chlor.  Just be careful that the Cyanuric Acid levels stay under 50 ppm.  The bleach and di-chlor program works and is a program I recommend.

[Jimmie]

Just to follow up on this. I added boric acid which tamed the pH. Hot tub water has been clear and a doddle to maintain since refilled at the end of December (5 months). Thanks all.