Water Chemistry Question

[Gytaryst]

3 years ago I sent a sample of my tap water to Ward Labs to have it analyzed. I plugged the results into Bru'n Water and used that for awhile. Then I read that municipal water can change fairly drastically over time so I wasn't sure how accurate my numbers were. I decided to start using 100% RO water and adding chemicals based on the Bru'n Water spreadsheet. I know the RO water is 4.4% TDS with a pH of 6.8.

On the batch I'm getting ready to brew I decided to use the "Pale Ale Profile" in Bru'n Water. I came up with 1.5 grams/gal of gypsum, 0.3 grams/gal of calcium chloride and 0.5 grams/gal of epsom salt. I've never gone over 0.75 grams/gal for any addition. I remember John Palmer saying not to overdo brewing salt additions or you could end up with a mineral water taste, (I don't remember if it was in one of his books or on youtube).

My question(s):
Is 1.5 grams/gal of gypsum excessive?
Is it okay to start with 100% RO water?
Is it better to use municipal tap water and, if so, how often should I send samples off to ensure the water I'm using matches the numbers I'm using?
How accurate is the LaMotte BrewLab kit?
Am I better off sending samples to Ward Labs?

Thanks

 

[mabrungard]

It's not universally true that municipal water quality changes drastically. It depends on the water source. If its groundwater, then its often more consistent. Surface water can change a bit and if the water supplier uses both, then the quality can vary drastically.

4.4%?? Are you sure of the units? Percent is the same as saying pph (part per hundred). I typically see TDS from RO machines in the 5 to 50 ppm range.

Regarding the tap water, if you have a TDS meter, you can perform a modest assessment of water quality and variability with that unit. However, its probably better to use a couple of aquarium water kits (Ca and Alkalinity) to monitor those important components. Getting a Ward test on the tap water is wise. Testing that same water with all the methods above will help you understand what the lab results mean in respect to the home tests. If you do see significant variation in the home test results in the future, you could collect another sample for Ward testing.

1.5 g/gal gypsum is a healthy dose, but not excessive in something like a PA. It's OK to start with RO, but you do need to include a yeast nutrient that has zinc in it. RO strips the zinc.

 

[Gytaryst]

Thanks. It is 4.4 ppm, sorry.
I think I will send off another sample of tap water to Ward Labs. I sent the last sample 3 years ago so if it's close I guess I can assume it's pretty consistent. According to the website for my city:
"All of the water supplied comes from nine wells that pump groundwater from the West Valley Salt River Subbasin."

 

[adixon3]

If your water supplier has a website they may release an annual water report you may be able to get there latest water readings and plug those readings into Bru'n water and compare that to what you get back from Ward Labs. It may save you some time in the future.