Water chemistry questions...

[Pilotwerx]

I finally bucked up and bought the K-2006 and speedstir. Last night was the first time trying it and I am slightly confused with the cya. The hot tub was just converted to salt.

FC - 8 ppm
CC - 9.2 ppm
pH - 7.8
ALK - 110
Hardness - 250
CYA - the black dot disappeared with 1/2" of fluid.

It is pretty clear I need to turn the SWG down to lower the FC. It also appears that have 1.2 ppm of residual. I was under the impression, since there is an ozone generator, that the ozone would knock the residual down. Or am I out in left field without a glove on that one?

The perplexing part is the CYA. After adding about a 1/2" of fluid to the tube, the black dot disappears. I know they are not great, but my hth test strips showed between 50 and 100 ppm CYA. Any idea what could be wrong?

Any incite is appreciated....

 

[Sunandsky]

If the black dot disappeared before the water level reached the "100" mark, that means your CYA is over 100.

You can find instructions on the forum for diluting your pool/spa water sample by 50%, re-running the test, then multiplying your result by 2.

If you have a kit with the squeeze bottle with lines at 7 ml and 14 ml, fill it up to 7 mls with pool/spa water, then fill to 14 mls with tap water, shake to mix and squeeze out 7 mils so you are back to the 7 ml line. Then add the reagent and run the test as you did. Multiply results by two.

 

[JVTrain]

A bit confused on your results. Is the CC you listed actually the TC (total chlorine). TC = FC + CC If that is the case your CC is 1.2 ppm. Still high and I would be concerned about that especially with an ozonator running that should help to dissipate CCs. You may need to SLAM the tub or consider draining/refilling. I would especially consider a drain, deep clean with a product such as Ahh-some and refill because of your high CYA. Trust the K-2006 over the strips. I'm unfamiliar with the exact measurements of the K-2006 CYA measuring tube. What level of CYA is indicated on the side of the tube at this "1/2" of fluid" level?

Before converting to salt, how were you chlorinating?

 

[pabeader]

They already said what I was going to say...

 

[Pilotwerx]

Sorry for the confusion. The CC was 1.2 ppm. My house water is supplied by a well and does not have the ability to fill the tub. When I had my pool closed, the pool company filled the tub with pool water. Since they maintain the pool during the summer for my wife and I (I travel for consecutive weeks) I did not think there would be an issue nor did they. I have been doing this for years. The pool was converted to salt two weeks before closing. Prior to that it was chlorinated with trichlor and the tub was chlorinated with dichlor.

I am guessing from above, that this a battle I cannot win... If I can drop the CC will the high CYA still make it unusable?

 

[JVTrain]

In order to maintain adequate sanitation, you'll need to maintain very high FC levels. When your CYA is that high, most FC is bound to CYA so is not available for sanitation. You would have to constantly maintain FC levels above 10 ppm to maintain enough available chlorine for sanitation, depending on what your actual CYA is at. Could you do a series of partial drains, refilling with well water? That is assuming that the well water won't cause other issues such as iron staining.

 

[Pilotwerx]

Retested again... The speed stir is addicting!

FC 8
CC 1
PH 7.6
Alk 110
CH 250
CYA 120 (using dilution)

I am a little surprised it is that high. But then again I am not surprised seeing the pool company felt the need to note they were not a fan of the variable speed pump, the control panel I built and the fact I went with salt instead of spending $500+ a year on chlorine. With the cya that high, I now understand that cost.

I am going to look for a tank to fill up at my business. Although it too is a well, it is connected to a spring that produces 100+GPM and artesians 8000 gallons a day to a trout pond.

Your help is greatly appreciated!

 

[Swampwoman]

Hi pilotwerx.
What is the capacity/gallonage of your hot tub?
And do you have softened water in the house?
What is the gpm on your well? I'd be surprised if you couldn't get a hot tubs worth out of it...pool may be another story...if you have enough hose to get to it, that is...

Before I switched to dual tanks, I still had 1400 gal capacity out of the softener before regeneration (now doube that with my dual tanks). My hot tub is small. I have one outdoor faucet plumbed to the softener but in the winter to change water I run it from a shop sink in my studio, which is well.

When using well water (lotsa iron) I use a prefresh mechanical filter on the end of a hose to attempt to reduce iron load and use metal control spa product to sequester. In pool season, I just use the soft water and add calcium.

If your well can handle a few hundred gallons at a time, those are both options that would allow you to dilute your cya. In the interim, consider shocking with liquid chlorine to try to break down those ccs...

Also, even with swg and ozone (the latter which also eats fc) you may stilltill need to oxidize nw and ten to avoid cc buildup. To oxidize with liquid chlorine normlly means adding an extra 7 ppm per person per hour used.

Hope that helps!

 

[Pilotwerx]

The problem with my well is recharge. I have an 85 gallon pressure tank that takes four hours to fill. There is no iron but I do run a softener. The pool usually holds its own with just the addition from rain. The irony is that I spent many years designing the process systems for the largest spring water bottling plants in the country. On a good day, I can typically get around 150 gallons before it is empty. At some point I am going to gamble with fracking it to see if it helps.

The tub is 400 gallons. This weekend I am going to drain it down and try to refill with the well. Like you, in the winter I run a hose from a line in my garage.

I do have to say, for the money, the hot tub swg is an impressive little unit.