I posted this in the everything else thread, but didn't get a response. Figured all of the chemical experts hang out here. My CH has been consistent in the 100-125 range for 2 years now. (Sometimes I get 4 drops until the color change, sometimes 5). I am having heater issues and I dug up my heater manual (Hayward 200,000 BTU 3 years old) and it said I should maintain my CH at a minimum of 200, or the I risk corrosion to the Heat Exchanger. Also it says to maintain chlorine in the 1-3 ppm range. So I know they are wrong there and I figure they are just repeating industry standards. Should I increase my CH and worry about this? Everything I have learned on this site says not to worry about CH for a vinyl pool. Thanks!
Calcium Hardness Vinyl Pool with Heater
- Thread starter Kjp300
- Start date
- Jul 21, 2013
- 52,864
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Yes, increase your CH a bit. A CH level around 250 can prevent scale buildup in a gas heater.
Your signature does not show the model heater you have.
Your signature does not show the model heater you have.
Pool math says to add 32 pounds of calcium chloride. I will start with 22 pounds, test, and add more as needed. Do I just purchase this at a pool store and dump it in the pool all at one time? Is there a technique to adding the suggested amount? Will it cloud the pool for a while? Thanks for any suggestions!
- Jul 21, 2013
- 52,864
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
From Recommended Pool Chemicals - Trouble Free Pool
CH – Calcium Hardness
Calcium hardness can be raised with calcium chloride or calcium chloride dihydrate. They are available in some areas as Peladow, Dowflake, Tetra Flake, or Tetra 94, often sold as a deicer by hardware stores, and some big box stores, in colder climates. Pool stores will carry either calcium chloride or calcium chloride dihydrate under a variety of names, including Hardness Plus, Balance Pak 300, Calcium Hardness Increaser, etc. Calcium products should be spread across the surface of the deep end of the pool.
Mixing calcium in water will generate a lot of heat. Do not mix calcium in a bucket of water before you add it to the pool.
CH – Calcium Hardness
Calcium hardness can be raised with calcium chloride or calcium chloride dihydrate. They are available in some areas as Peladow, Dowflake, Tetra Flake, or Tetra 94, often sold as a deicer by hardware stores, and some big box stores, in colder climates. Pool stores will carry either calcium chloride or calcium chloride dihydrate under a variety of names, including Hardness Plus, Balance Pak 300, Calcium Hardness Increaser, etc. Calcium products should be spread across the surface of the deep end of the pool.
Mixing calcium in water will generate a lot of heat. Do not mix calcium in a bucket of water before you add it to the pool.
I have a vinyl liner and a heater as well. My fill water also tends to run low in the Calcium department, with an average around 50 - 75. After first joining TFP a couple of years ago, I quickly learned that a vinyl pool doesn't need calcium (unfortunately, after dumping in a TON of Calcium Hardness Plus after being pool stored for my first and last time).
Long after my levels dropped to their naturally low state, I read that a heater needs some calcium (according to their guidelines). I found a thread where a MOD had stated that low CH for a heater was not going to damage it. Low pH would, but not low calcium levels, so I have not been maintaining the minimum recommended level.
I wonder which is truly the correct answer? I've seen both answers and certainly don't want to do anything that could lessen the lifespan of my heater! I suppose following the manufacturer's recommendation is the way to go....
Long after my levels dropped to their naturally low state, I read that a heater needs some calcium (according to their guidelines). I found a thread where a MOD had stated that low CH for a heater was not going to damage it. Low pH would, but not low calcium levels, so I have not been maintaining the minimum recommended level.
I wonder which is truly the correct answer? I've seen both answers and certainly don't want to do anything that could lessen the lifespan of my heater! I suppose following the manufacturer's recommendation is the way to go....
Any other Mods care to join in? Even though a vinyl pool doesn’t require calcium I figure that raising the level to 250 won’t hurt the pool water or affect the pool. I have read that soft water can be corrosive to pipes etc. Now I am the farthest thing from a chemist so I really don’t know how soft the water has to be before it is corrosive.
As far as PH, I test daily or every other day to make sure it is in the proper range. I check all of my numbers but after reading the posts on this site for the past two years, I surmise that, if at the minimum, you keep your FC at the proper levels based on your CYA and keep your PH between 7.2-7.8 your pool will be sparkling and most water problems will be avoided. And to do that takes only about 10 minutes a day.
As far as PH, I test daily or every other day to make sure it is in the proper range. I check all of my numbers but after reading the posts on this site for the past two years, I surmise that, if at the minimum, you keep your FC at the proper levels based on your CYA and keep your PH between 7.2-7.8 your pool will be sparkling and most water problems will be avoided. And to do that takes only about 10 minutes a day.
- Jun 22, 2014
- 47,857
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
As I recall, the calcium requirement was an old standard that was carried-over from boiler systems and such. There may have been other reasons, but it became an industry standard of sorts. The two biggest enemies of a heater are low pH (erosion) and a high CH (scale). I don't believe low CH was major concern for residential pool heaters, but I'll defer to @JoyfulNoise as I believe he was the on who clarified this for us before. Stand by,
I know of no damage, including scale, that is the result of high or low calcium (within reason). pH is by far the big culprit as it can corrode metal at low pH and cause calcium precipitation with high pH but the takeaway is to keep your pH within TFP guidelines
- May 23, 2015
- 24,444
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Heaters tend to build up a thin layer of calcium carbonate on their internal surfaces over time. This thin layer acts as a barrier to physical metal erosion (from high flow rates of water) and chemical attack (from accidental pH drop). However, this film is not indestructible and it can come and go over time depending on CH and pH levels. Low CH inhibits this film formation and leaves the internal metal surfaces more exposed to pool water. There is no way to precisely assess the quality of this scale layer but having some CH will assure that it is present. Around the 45sec mark in this video shows what the heat exchanger tubes look like from chemical & physical erosion -
Very high CH can lead to thick and flaky scale formation inside the heat exchanger that can be highly detrimental to it. The coils can get plugged up with scale which can lead to over-boiling of the water, banging or knocking sounds, and/or a plugged up header/bypass. All of these can shorten the life of a heater and lead to less efficient heating. See this thread for what scale can do to a heater -
www.troublefreepool.com
Keeping the CH around the minimum recommended value, ~ 200ppm, seems to be a reasonable compromise between the formation and maintenance of a thin scale layer and low risk of boiler scale.
Chronically low CH leaves the heater more susceptible to chemical attack should the other chemical levels get out of range.
Very high CH can lead to thick and flaky scale formation inside the heat exchanger that can be highly detrimental to it. The coils can get plugged up with scale which can lead to over-boiling of the water, banging or knocking sounds, and/or a plugged up header/bypass. All of these can shorten the life of a heater and lead to less efficient heating. See this thread for what scale can do to a heater -
Pentair Mastertemp 250 Service Heater Issues
Hello all. Newbie here hoping to find some assistance. I have a Pentair Mastertemp 250 pool heater. When the heater is turned on, after a variable amount of time the service heater light comes on. It is almost always within the first 10 minutes of operation. Once the service heater light comes...
www.troublefreepool.com
Keeping the CH around the minimum recommended value, ~ 200ppm, seems to be a reasonable compromise between the formation and maintenance of a thin scale layer and low risk of boiler scale.
Chronically low CH leaves the heater more susceptible to chemical attack should the other chemical levels get out of range.
Thanks for taking the time to post such a detailed explanation. This site is invaluable. I will raise my CH.
- May 16, 2015
- 64
- Pool Size
- 16000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Great information here - thanks everyone! I also have a vinyl pool with heater as well as a rock waterfall feature. If my CH is low, I will start finding small mortar pieces in the pool from the waterfall returns. My CH is currently at 110 so based on what I'm reading here, would ~200 be sufficient?
I'm always nervous adding calcium to the pool. I follow guidelines here to spread it over the deep end instead of premixing in a bucket, but I end up with the SWG giving cell errors after a day and then taking off the cell and having to clean it in acid wash. Does anyone use the bucket premix method and would it be better in my case or is that no-no?
I'm always nervous adding calcium to the pool. I follow guidelines here to spread it over the deep end instead of premixing in a bucket, but I end up with the SWG giving cell errors after a day and then taking off the cell and having to clean it in acid wash. Does anyone use the bucket premix method and would it be better in my case or is that no-no?
I always premix calcium in a bucket before dumping it in pool. I do it for many years and never add issues. Before doing this it was never fully dissolved and required A LOT of brushing. It is true that the water in the bucket will become hot so be cautious.
I too am nervous about adding calcium directly to the pool....but also nervous about pre-mixing it. The first and only time I've added it before, I did it before finding TFP and dumped it into the deep end. I must not have moved it around that well, because it left white spots on my liner. Grrr... Scared that will happen again.
If you mix in a 5 gallon bucket, how much calcium should you limit per batch given the thermal reaction? I need to add almost 50 lbs and I don't want to do anything stupid! haha
If you mix in a 5 gallon bucket, how much calcium should you limit per batch given the thermal reaction? I need to add almost 50 lbs and I don't want to do anything stupid! haha
- May 23, 2015
- 24,444
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Use cal-hypo to chlorinate instead. You get the FC along with the CH increase and you can slowly add it over time.
CH isn’t going to solve “mortar bits” in the pool from the waterfall. That’s simple mechanical erosion. I get stone bits all the time and my CH is up at 1000ppm.
CH isn’t going to solve “mortar bits” in the pool from the waterfall. That’s simple mechanical erosion. I get stone bits all the time and my CH is up at 1000ppm.
@JoyfulNoise
I’d like to hear more about low calcium as it doesn’t seem to match what we’ve seen on the forum in the past. In this thread members seemed to somewhat state opposite? As one who enjoyed learning I’d love to hear more from you on this?
I’d like to hear more about low calcium as it doesn’t seem to match what we’ve seen on the forum in the past. In this thread members seemed to somewhat state opposite? As one who enjoyed learning I’d love to hear more from you on this?
- May 23, 2015
- 24,444
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
@JasonLion @chem geek and waterbear (I’m assuming that is who “Guest” is after he asked to have his account shutdown and all of his personally identifying info erased) are welcome to come back anytime and comment. I’d be happy to have a discussion regarding the vast field of study that is corrosion science with respect to heat transfer equipment....
I added 20 pounds of Calcium Chloride by spreading it in the deep end of the pool in front of the return. Salt cell still working and didn't have any trouble with it dissolving. I did have to brush it around a bit. Guess I was just lucky.
- May 16, 2015
- 64
- Pool Size
- 16000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
I recently added 10lbs to my pool. I used a 5 gallon bucket, filled it about 3/4 with pool water, and added 5lbs of the calcium. Stirred until completely dissolved and then poured into the deep end. I waited several hours and repeated the process with the next 5lbs. I had no issue this time with my salt cell giving error. The process may be overkill, but it worked for me.