Chlorine turns spa translucent green

[donws]

Hi all,

I have a 2008 Sundance Cameo (450 gal) spa with ozone. To date I've been using Sundance's Nature2 equivalent (MPS + mineral cartridges) with mostly positive results. But after stumbling across the dichlor-then-bleach method, I decided to give it a try.

Today I drained the spa, flushed with Sea Klear system flush, filled it from my well through a "prefresh" filter (as always) and then balanced the water per the recipe (my TA is ~60ppm, PH is ~7.8, and CH is ~130). I also added about 1.5 cups of ProTeam's Gentle Spa to yield ~50 ppm borates.

After balancing the water, it looked sparkling clean. Then I shocked using dichlor to about 10ppm (~1oz dry weight dichlor). The water turned green immediately, not a cloudy green, but more translucent. This has never happened to me before, but to be honest I never added more than a tablespoon or so of dichlor at one time for the weekly shock (i.e., MPS was used for daily oxidation).

I suspect the cause is metal in my well water (likely copper?) but before I add a metal sequestering agent (like Leisure Time's Metal Gone) I thought I'd seek other opinions from knowledgeable folks on this forum. My preference is to add as few chemicals as possible to evaluate how well dichlor-then-bleach works alone, but if I need to add a metal remover to prevent spa shell staining, I certainly will!

Thanks!
Don

 

[techguy]

It is a metal and I will let a metals expert help you. I don't think the Leisure Time is one of the recommended products (I could be wrong).

 

[jblizzle]

Sounds like metal to me as well. I was going to say that the Nature2 was a likely cause (we NEVER recommend adding metal to the water intentionally due to to possible staining), but then realized you have just replaced all the water.

Here is the article in Pool School about dealing with metal: pool-school/metal%20stains

 

[donws]

Thanks guys. I had a little Metal Gone on hand (only about 4oz) so I added it to the spa. It seems to have helped a bit and the green tint seems to be fading as the FC level drops. I'll check it again in 24 hours, perhaps rinse the filter, and if needed pick-up some additional metal sequestering product.

I had noticed a mild "green" tint in the past during weekly dichlor shocks (3-4 tsp), but not to the extent that this 1oz (10ppm) shock produced.

Don

 

[chem geek]

It's more likely that your well water has iron in it and that it is yellow but against a bluish background looks green. Is your spa color bluish? It may be easier for you to use a metal trap filter when filling your spa so that way you don't need to deal with a metal sequestrant. Was your "prefresh" filter supposed to filter out metals? Perhaps that isn't working or doesn't get the metal level low enough to prevent coloration.

 

[donws]

Chem Geek,

The spa shell is white/pearl so the water is definitely more green than blue. This is the first time I've used a "prefilter" (it was called "Prefresh" by spadepot.com) and it is supposed to remove metals (KDF and active carbon). I don't know how well it works in this regard, but it took forever to fill the spa through the filter (nowhere near the 2.5 gal/min flow advertised) so I probably won't use it next time. I already have a whole house sediment filter for the house and (possibly aside from metals) the well water is quite good.

I've noticed a slight green tint to the water after prior weekly dichlor shocks (per Nature2 recipe) but since I've never shocked to this level (10ppm) the green was never as noticeable.

The spa's (new) filter has now also turned quite brownish. Maybe this is precipitated iron and/or copper being captured? Since I did a thorough cleaning (Sea Klear System Flush) before the fresh fill (and the water looked sparkly before the Dichlor) I don't think the accumulation is "gunk" from the plumbing. I'll take another look and rinse the filter this evening when I check the water balance and chlorine demand.

Thanks again for your suggestions. Very much appreciated.

Don

 

[chem geek]

The brown in the filter is probably precipitated iron. Sounds like you have significant metals in the water and it's too bad the fill water filter isn't able to handle it.

 

[donws]

I rechecked FC after ~24 hours. The FC dropped to about 2.0 ppm which indicates a higher CD (10.0 ppm down to 2.0 ppm) than I expected, although the tub does have 24hr low speed circulation with ozone. Good news: At 2.0 ppm FC, the water is no longer tinted green and it remained clear after adding ~0.2 oz more dichlor to increase FC levels just above 4ppm.

I'll probably still pickup some Proteam Metal Magic and/or a different pre-filter for future refills.

Given the relatively high CD, should I do another shock to 10 ppm with dichlor now, or perhaps using bleach in a week or two when I switch over from dichlor?

Thanks,
Don

 

[chem geek]

I'd bring it up to 10 ppm again using Dichlor (if your CYA isn't yet to 30-40 ppm) and see if it holds better. You might have some leftover chlorine demand from something in the water. Let's see if it changes. I would doubt that only 2 hours of an ozonator would be the cause.