# LSI and new Jandy JXI 400 propane heater

#### kraftchick

Silver Supporter
Just had a Jandy JXI 400 propane heater installed yesterday (didn't expect to be able to do a heater this season, but one was available and installer had an opening.....plumbed and electric hook-up yesterday), working on propane hook-up. Installer was discussing LSI with me and impact on the heat exchanger over time. I explained that I do a pretty good job maintaining proper levels with a TF-100 kit on a weekly basis, but have not paid attention to LSI calculations. Ours is a vinyl pool and maybe mistakenly I've not really focused on CH level because of the vinyl....but he said I'd definitely want to pay attention to that and bring that level up. Below are my current numbers and you can see CH is 25. I downloaded the Orenda calculator and with my numbers the LSI is pretty far out of wack. I've also read a few threads here discussing CSI calculation vs LSI....so which should I follow? Looks like the Pool Math app has CSI logging and the Orenda app is LSI.....thoughts on which to follow to "properly" balance my water.....goal being to extend the life of the heater equipment?

FC 4.0
CC 0
pH 7.7
TA 60
CH 25
CYA 50
Temp 80F

#### kraftchick

Silver Supporter
Should add, that the installer suggested bringing CH up to 400. Plugging that number into Pool Math brings CSI from -1.22 to -0.03, in range. In the Orenda app, taking CH to 400 brings LSI from -1.30 to -0.18. So I think this is pretty conclusive that on my current numbers adjusting the CH to a better level would help....just wanted thoughts by the pros here at TFP, and what's recommended to use CSI or LSI calculation?

#### ajw22

Gold Supporter
TFP Guide
We recommend you follow our CSI as calculated in PoolMath

CH level of at least 200 is recommended with a gas heater.

#### kraftchick

Silver Supporter
Thanks ajw....plugging in my numbers into Pool Math for CSI shows a CH of 200 would put me at -0.46 and CH of 300 would put me at -0.29

#### JamesW

TFP Expert
The CSI and LSI should be very close if you do them correctly.

Some apps require the corrected alkalinity (carbonate alkalinity) vs. the total alkalinity.

So, make sure that you are using the right numbers.

#### ajw22

Gold Supporter
TFP Guide

CSI will bounce around with pH and water temperature. pH of 7.8 will raise your CSI.

TFP Expert

#### JamesW

TFP Expert
They are pretty close.

#### kraftchick

Silver Supporter
Meant to post these numbers earlier this morning and also thank everybody for the help. All looks good....but FC and pH both went up. I boosted the pump speed overnight to help it mix the 45lbs of calcium that I put in yesterday evening (mixed in bucket).....and I'm thinking the FC went up because I didn't drop the output of the chlorinator to compensate for the increase in flow that it normally sees overnight (which is usually my lowest rpm of the day), and I had the solar cover on all day due to cloudiness, so no sun deterioration either. I haven't tried to bring down pH yet as I wanted to give a day and will check in the morning before pulling it down with acid

FC 7.5
pH 8.1
TA 70
CH 300
CYA 60
Temp 80F
CSI .29

JamesW
Hello , This is an inactive thread. Any new postings here are unlikely to be seen or responded to by other members. You will get much more visibility by Starting A New Thread

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