Green mold in Spa in Winter. Time for purge?

[Stoots]

Hi all,

I have an in ground spa (1000 gallons) that we keep open in the winter. We have a teal color mold forming at the water line in our spa. After doing some research, I have to come to the conclusion that I need some Ahh-some Clarity. My question is this, can I purge/drain/refill the spa while the temps are below freezing? I am in Northern IL and I would like to get rid of this growth. But worried about pipes freezing.

 

[Bperry]

Hi all,

I have an in ground spa (1000 gallons) that we keep open in the winter. We have a teal color mold forming at the water line in our spa. After doing some research, I have to come to the conclusion that I need some Ahh-some Clarity. My question is this, can I purge/drain/refill the spa while the temps are below freezing? I am in Northern IL and I would like to get rid of this growth. But worried about pipes freezing.

Teal color sounds like maybe copper staining. You can try rubbing a trichlor tablet on it to see if it comes off. If it does, it’s algae.

 

[Mdragger88]

How are you sanitizing the spa in the winter? (I assume you use your swcg in the summer).
Can you share your latest test results with us?
Fc
Cc
Ph
Ta
Ch
Cya

 

[Stoots]

How are you sanitizing the spa in the winter? (I assume you use your swcg in the summer).
Can you share your latest test results with us?
Fc
Cc
Ph
Ta
Ch
Cya

FC - 3
CC 1.5
PH 7.2
TA 0
CYA 0
CH - inconclusive probably due to metals in the water.
At this point I think this sticky gunk is from the plumbing and needs to be purged.

 

[Stoots]

So I tested again this afternoon:
FC - 1
CC 1
PH 5.4
TA 10
CYA 0 - Hot tub is always covered so never really focused on this.
CH - initial color is Pink and never turns to blue no matter the number of drops.
I am working to first adjust PH up to 7.2.

 

[ajw22]

I am working to first adjust PH up to 7.2.

How are you doing that?

You need to raise your TA with baking soda to raise the pH.

You need CYA to buffer the harshness of chlorine.

You need more chlorine to kill the mold.

Best thing you can do is dump that water and start with fresh water.

 

[Mdragger88]

I’m thinking maybe you’re corroding your heater that’s why you’re seeing green/blue/teal - how/why did the ph get so low?
Have you been using dichlor/trichlor?
What kind of filter do you have?
If its a cartridge what does it look like?
Is this spa connected to the pool at all or completely separate?
Definitely need to drain & start over as AJ said but you want to prevent this corrosive condition in the future as well.
It looks like the weather is only actually freezing there for short periods so it should be fine to purge, drain (quickly with a submersible pump) & refill quickly so long as the water is flowing. Then get the tub heating back up.
Then follow this guide if its a separate body of water from the pool.

How do I use Chlorine in my Spa (or pool)?

If you have a question about any information within this Sticky, please start a new thread for yourself where you will receive very quick responses to your specific questions. Thank you! Introduction There are two main things to consider when maintaining your hot tub water, Water Balance and...

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[JamesW]

Pictures?