Chloramine problem

[thecheese]

Hi, I have a Marquis Epic Signature hot tub 450 gallons, using the FrogEase smartchlor (set to 2, a week old) and minerals cartridge (set to 6, 3 months old).   The tub is in a covered house with little sun.  The water was about 2 months old with little usage, maybe 7 times.  Using a Taylor K-2006 test kit and separate MPS reagent kit, I was getting combined chlorine of 12.8ppm and free chlorine at 1.8ppm.  CYA was maybe 60 to 70 (I could still sort of slightly see the black dot at bottom of tube).   I had tried to lower the CC w/ MPS (Oxy-Spa non-chlorine shock) by using 2 oz a day for like 3 days.  I also used dichlor (2 oz/day for another 3 days).  That didn't seem to lower the CC much and I could still smell a strong odor.

So, I decided to dump half of the water and refill with new water using a new water hose filter I bought.  New readings:

Alkalinity: 50PPM ( just added some chemicals to boost it up to 100ppm, will test tomorrow)

Hardness: 95PPM

CYA: 45

Free Chlorine: 0.8 PPM

Combined Chlorine: 8.2 PPM

MPS: 2PPM (Monopersulfate compound).  Is this normal?

I'm not sure how to get the CC down.  In the Taylor booklet, it says MPS doesn't lower CC, but when I spoke w/ Spa Depot, they said their Oxy-SPA shock (MPS) does lower CC.

The Taylor book also said to use chlorine at 10 x the CC level to create a superchlorination.   It also said to use non-stabilized chlorine (liquid bleach?) b/c stabilized (Dichlor) would increase the CYA.  However, when I was searching the web, it seems people say don't use liquid bleach in hot tubs (rots o rings, harms hot tub finish, etc.).   I'm confused.

Do my test results seem realistic?   Had to use 41 drops to get the CC.  Starting to run out of test chemicals.  Not sure what I'm doing wrong.

It seems like every time I change the water, after like a month or two, the balance seems to out of whack very quickly (turns cloudy, green, foam, etc.).  That is why I didn't want to do a full change of water this time.

Thanks for any help.  It's driving me nuts.

 

 

 

 

 

 

 

[RDspaguy]

Ok... where to begin?

For starters, read about the dichlor/bleach method in the water chemistry section. This should help clear up your cya misunderstanding.

Any oxidizer will burn off chloramines, including mps. Some are more effective and efficient than others, but oxidation is oxidation regardless of the source.

Mps will throw off your chlorine readings.

I have heard that smartchlor can read as cc, but don't know a great deal about it.

30ppm cya is ideal, over 50 is dump time in my opinion. No cya can cause the issues you mention, but once your cya is around 30ppm liquid chlorine will not cause any problems.

A private spa should be drained and refilled at least 3-4 times per year. Not half-drained, completely drained and refilled, every 3-4 months. 

@waterbear, anything to add?

 

[thecheese]

So, do you suggest that I add more MPS?  If so, how much more?   The directions I see seem to refer to number of bathers.  Haven't seen anything like to lower CC by X amount, use Y amount of MPS.   So, what is the most effective oxidizer to use then to reduce CC?

I'm using the Taylor K-2041 Reagent Pack, Monopersulfate Interference Remover (for 2000 Series kits w/ .75oz reagents & K-1515-A) with my tests, so I'm hoping that is supposed to give me accurate CC readings.  But I guess if smartchlor and MPS both can interfere w/ CC tests, I'm not sure how to get an accurate reading then.

The odd thing is that when I tested the CC before without using the K-2041 reagent, the CC was lower before using the reagent.  I would have expected the CC to be lower after using the K-2041 reagent, but maybe there was a gap of a few days and I may have added some other chemicals between the tests.

Thanks.

[RDspaguy]

@waterbearis the chemistry expert, I just fix them. I have read a few threads about smartchlor issues on another forum, but have no personal experience with it.

[waterbear]

Your CYA is too high. That makes the free chlorine less effective. If your current CYA is 45 ppm you want to shock to 15-18 ppm with bleach, not dichlor. Dichlor will add 9 ppm CYA for every 10 ppm FC added. Bleach does not add CYA. 1 oz of 6% unscented chlorine laundry bleach with no thickeners or other additives will raise 450 gallons just slightly over 1 ppm so if you are currently at, say, 5 ppm FC you will need to add 10 -12 oz of bleach to shock.

On 1/1/2021 at 6:01 AM, thecheese said:

It seems like every time I change the water, after like a month or two, the balance seems to out of whack very quickly (turns cloudy, green, foam, etc.).  That is why I didn't want to do a full change of water this time.

NO surprise here. Smartchlor is 1,3-Dichloro-5,5-Dimethyl Hydantoin and is a stabilized form of chlorine which tends to stay bound to the hydantion base molecule. This will test as CC on your test kit and the MPS further adds to the problem.

My suggestion is get rid of the frog, it's very expensive and, IMHO, creates more problems then it solves if you are actually trying to test and balance your water.