Yellowish/green tint in hot tub. Test results included. Please advise!

[BQ]

I have an 8x10 fiberglass rectangle hot tub. (Approx. 1200 gal) My water all of a sudden turned this greenish yellowish color. The only thing that has changed is I added a thermometer that has a turtle on top. Like seen here:
Amazon.com : Pool Spa Jacuzzi Hot Tub Floating Animal Thermometer F/ C Display-- Turtle : Swimming Pool Heating Products : Patio, Lawn Garden

Here are my test results:
TA = 70
CYA = 0. (No change in color)
FC = 3.5 ppm
CC = .5 - 1 ppm
CH = 100
PH = 7.2

Any advice is greatly appreciated!

Bq

 

[JamesW]

The two main things that I can think of are bromine or iron.

Elemental bromine can color water when the bromine level is very high and the ph is low. Your results don't seem to support it being due to elemental bromine.

Iron should have been obvious from the start.

How long ago was the tub filled?

What is your routine for chemistry testing and additions?

 

[JoyfulNoise]

How do the walls feel? Are they slimy? How old is the water?

How do you disinfect the hot tub between and during soaks?

You are showing FC and CC which means you are using chlorine but you have 0 ppm CYA. If you have 3.5ppm FC with 0 CYA, then your active chlorine levels (hypochlorous acid) are going to be intolerably high making the spa water very harsh on your skin and clothes.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

 

[BQ]

It's a salt water hot tub filtered through a pentair DE filter that does my pool during the summer as well. That was cleaned at the end of the season. Hot tub has been used regularly with no issues, until today. Salt was low last week @2400, but added salt and now it's 4200. A bit high, but don't think that should be a problem. The water was interchanged weekly when the pool was open. Now it's just the same water from then. I don't use bromine and haven't had Iron issues in any of our water tests inside the house or in the pool. Filled pool with hoses. 2 years ago.
Walls aren't particularly slimy, unlike when the pool gets slimy, for certain.

 

[JoyfulNoise]

I guess I'm confused by your plumbing - this is a stand-alone hot tub but it's hooked up to your pool plumbing? Where is the chlorine coming from, the pool's SWG?

How often are you testing and dosing the spa water? It sounds like you're using strips based on you reporting the CYA showed no color change. Can you please run a full battery of water tests using your good test kit, not strips?


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

 

[Isaac-1]

I agree with the others, this sounds like a metals build up issue, and test strips are too inaccurate to provide meaningful numbers. Based on the limited information so far, my theory, and that is all it is at the moment, is that before you added salt last week your SWG was running at below optimal levels, then you added salt and left the SWG running at the same setting level, with the salt back in the optimal range the SWG actually produced more FC as the SWG setting is just percentage run time, not some measure of actual production. Therefore your FC built up slowly, and at some point you reached a tipping point with the elevated FC and metals that may have built up over time in your water started to participate out of solution causing the visible color change.

Ike

p.s. even though you have had your water tested for metals, they can still get into your water through various outside sources (fertilizer, etc.) and the common tests can show false negatives when the levels are low in your fill water. These levels cant then build over time due to evaporation condensing the levels in the water, etc.

 

[BQ]

I guess I'm confused by your plumbing - this is a stand-alone hot tub but it's hooked up to your pool plumbing? Where is the chlorine coming from, the pool's SWG?

How often are you testing and dosing the spa water? It sounds like you're using strips based on you reporting the CYA showed no color change. Can you please run a full battery of water tests using your good test kit, not strips?


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

I use the TFP kit to test. No strips. The cya test when I added the r-0013, the solution never changed, and I was able to see the black dot when filling the clear tube to top.

The hot tub uses the same equipment as the pool via an actuator that switches the plumbing from spa to pool, except when the pool is closed.

I will see if I can get a test done for metals at the store. I'm just cautious that they just will blame phosphates or something else that they throw out there. Would a photo of the color help?

 

[JoyfulNoise]

Ask them to test specifically for metals and ignore anything they tell you.

As I stated in my first reply, 3.5ppm FC with NO CYA, is a really bad place to be in. Your water will have extremely high levels of hypochlorous acid in it which will not only be irritating to your skin, eyes and nose but is also not good in anyway for your Spa's internal equipment. Normally one would operate a hot tub with at least 30ppm CYA so that the hypochlorous acid levels would be moderated down to below 0.1ppm.

How did your CYA get so low? If the water in your tub came from your SWG pool, it doesn't make sense that the CYA would be zero as it would take a long time for it to be oxidized by chlorine.

Something is not right here. Are you sure your CYA tests are accurate/correct? How old is your test kit?


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006

 

[BQ]

My test kit is about a year old. I'll retest it, but what would be the fix! Drain and fill?

 

[northrn]

Would a photo of the color help?

Yes, please.