Calcium Level, Salty hottub, LSI and salt generator scaling

Feb 17, 2018
22
UK
G'day all,

I have purged and started with fresh water in my Hotspring Relay with Freshwater Salt System (1290L/350 Gallons), it's a new tub but the amount of gunk that Ahhsome pulled out is quite outstanding, highly recommended for anyone with a new tub to get squeaky clean.

I could do with some views on water chemistry, particularly LSI vs Hotspring recommended ranges, reading around it appears that the thinking on fixed ranges has moved on in the context of LSI/CSI for pools and spas, I also note that most recommendations for CH are way above the Hotspring recommended levels.

Hotspring have a recommended range for CH of 25-75ppm target 50ppm (presumably to reduce Salt system scaling), the tub came with a water softener (we have 500ppm CaCO3 tap water in these parts so it's needed), it also came with their magic Calcium remover bag. When the tub was initially filled on delivery the CH looked to be in range according to their test strip (I don't yet have the means to get a more accurate CH test so I am relying on the test strip). I regenerated the water softener, measured it's output for hardness and filled the tub, the CH now looks to be around 100ppm, so the softener appears to have run out of steam (or the water is harder than a month ago) on this fill.

Hotspring Salt range is 1500-2000ppm, target 1750.

I have balanced the water but not yet added salt, I am balancing to get LSI in range and the numbers are very close to Hotspring recommendations apart from CH, here are my numbers today:

Temp: 39 C
pH 7.5 (Ceiling is 8.2/8.3)
TA 85
CH 100
CL 10, initial shock
CYA 12 (aiming for 30 at next Dichlor addition), no Hotspring recommendation for CYA.
Salt 0
LSI -0.25 no Hotspring recommendation for LSI

I want to be lazy and contain pH by letting it freerise to it's ceiling (also based on latest thinking related to pH levels) :eek:

When I increase the CYA to 30ppm and CH stays at 100ppm and I add salt to 1600ppm and if I let the pH free rise to its ceiling of 8.2 the LSI will change to 0.19.
If I do the above but reduce CH to 50ppm (presumably by using their magic bag rather than dilute the water) the LSI is -0.11.

Given the above would LSI of -0.11 create less scaling on the salt generator than 0.19? Is there much difference in the context of Calcium scaling between these two LSI readings?

As a separate note, we have higher than 2.5ppm Phosphates in the tap water here, so I treat that separately to get into the Hotspring range of under 150ppb (although I will start a separate thread for Phosphate removal as I am sure to have questions :D).

As usual, thanks for your thoughts 🍻
 
You should discuss your ideas with Hot Springs. We are happy to discuss TFP methods.


Of course, revert to manufacturer, It would be interesting to see if Hotspring would deviate from their standard instruction manual guidance (or lack of guidance), I doubt it.

Reading the forum further in the pool sections, it appears my question may have already been answered: 'keep the CSI between 0 and -0.3 and the salt cell will experience little scaling' paraphrased of course and I apply this concept to my tub and see what happens ...
 
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