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Green on the floor of hot tub

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Hi,

We have our tub for about 3 months. Over the last week or so we've notice green settlement on the floor. We use slow releasing tablets (4 in 1) and are very careful about checking levels - the chlorine, ph and alkalinity is always spot on. The strange thing about the green sediment is that if you disturb it it dissipates and dissipaters. It isn't until it settles again over night that it reappears. The photo shows what I mean.

https://imgur.com/a/OBjO2PV

Does anyone have any idea what this might be? I am unsure it fits the description of algae but I could be wrong.

thanks

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Try siphoning the green out to waste with a garden hose or the like and see if it keeps reappearing.  I would suggest it was just fine dust in the plumbing or filters (or maybe is coming from your cover) prior to the first fill, and is fine enough that the filters can't grab it.  If it keeps re-appearing and looks organic, I would try some algaecide (Don't go overboard in a small spa) and see if that clears it.

I often have a fine dust on the bottom, but not green.  I have a small battery powered spa broom to suck it up along with the grit that comes from the patio.

 

 

John

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Algea requires sunlight to grow. If you are using your cover I doubt it is algea. I am not a fan of algaecide in a spa, most are just adding copper to the water which could cause some problems, such as green stuff on the bottom of your spa.😁

Do you use a metal sequesterant?

@waterbear, any insight?

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17 hours ago, RDspaguy said:

Algea requires sunlight to grow. If you are using your cover I doubt it is algea. I am not a fan of algaecide in a spa, most are just adding copper to the water which could cause some problems, such as green stuff on the bottom of your spa.😁

Do you use a metal sequesterant?

@waterbear, any insight?

If your draining, cleaning, and refilling once in awhile, that little bit of copper from the algaecide shouldn't be a  problem.  There are also  copper free varieties if it's a concern.  A copper problem would be a nice emerald green water shade after a shock.  I learned that two years ago in my pool.  It was actually a nice color.  Metal Out resolved that rather quickly though.

 

 

John

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the 4 in 1 tabs usually contain copper but copper stain would deposit on the surface of the tub and would not easily dislodge.

Algae usually attached to the walls and has to be brushed off or is dispersed throughout the water, giving it a  a green tinge.

My guess is pollen or other fine plant matter which is carried by the wind and either floats on the surface or sinks to the bottom, and depending on the circulation from the jets, will  then usually collect in the same areas of the tub such as steps or ledges or it  is corrosion caused by a pH crash and subsequent damage to metal pump parts.

I really can't say more without a full set of test results. Saying that "the chlorine, ph and alkalinity is always spot on" does not impart any useful info. You said you use tablets and you stated you test for chlorine which means you are using trichlor, which is usually not recommended for hot tubs because of their very low pH which can damage tub parts and corrode metal pump parts if the pH crashes, which is a given for the small amount of water in tubs vs. pools. For this reason Dichlor (graunular stabilized cholorine) is normally used in tubs because it has an only slightly acid pH.

HOWEVER, if you are using stabilized chlorine exclusively you need to test for Cyanuric Acid since it will accumulate in the water. (Stabilized chlorine sources are chlorine chemicallly bound to cyanuric acid). Once Cyanuric acidd levels get too high it does not allow the chlorine to sanitize or kill algae since it stays bound to the cyahuric acid instead of being released as chlorine sanitizer.

Get a full test results (NOT done with test strips), post them, and we can take it from there. In the meantime I suggest reading:

https://www.poolspaforum.com/forum/index.php?/topic/23090-dichlorbleach-method-in-a-nutshell/

 

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Not many metal parts in a spa pump, but the heater element more than makes up for that if it's not the stainless steel one.

What color are your filters?

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3 hours ago, CanadianSpaTech said:

Is it new or new to you? Does it have a "salt" system?

 

On 8/1/2020 at 3:08 PM, hotubnewbie said:

 We use slow releasing tablets (4 in 1) and are very careful about checking levels - the chlorine, ph and alkalinity is always spot on

He is using trichlor in a floater, not a salt system.

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Getting lazy there Canadaguy. Must be all that delicious real maple syrup. Just say "No". We're here for you, buddy. We'll get through this together...😉

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@RDspaguy I asked if it was new or new to them because it could easily have been new to them but a used spa. Have seen several used spas that had "salt" systems but were improperly used/maintained when active or "decommissioned" but with the carbon electrode still in it and deteriorated down to chunky blue/green lumps. Usually in the Genesis systems. 

Think I will go make some maple bacon

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See there, that's why you're a spa guru! I want to be just like you if I ever grow up!

I hear they have a 12 step program for that habit of yours...🤣

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