Ca hardness question

moreira85

Well-known member
Nov 8, 2015
168
Boston, MA
Just changed my water in my 400 gal spa. After I filled it up I did a CA hardness test w my Taylor testing kit and got a reading of 30 ppm.
I added about 6 oz of CA increaser last night and when I tested it today I couldn’t get any reading of calcium? When I added the Reagent the water wouldn’t even turn red so CA was not even present today. I just added 5 more oz of CA increaser today.
what would make the CA hardness go down?
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,173
NY
. I just added 5 more oz of CA increaser today.
what would make the CA hardness go down?
Nothing can remove Calcium, CYA or salt except draining. Now, in a hot tub, splashout/refilling and rain can help ALOT faster than in a pool, but it is still a slooooooooooooow process. To go to 0 would require a full drain, and even then, you fill water would have at least some calcium in it.

Something else is amiss.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,310
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Only reason to add calcium to a plastic spa is to reduce foaming. Do you have a foaming issue?
 

moreira85

Well-known member
Nov 8, 2015
168
Boston, MA
Currently no foaming issue. I just can’t get the test to turn red when adding R0011. It starts to turn red then goes clear. So CA hardness isn’t important in a tub?
 
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