How to size a salt chlorine generator

How to Size a Salt Chlorine Generator for My Pool

Hello prospective salt chlorine generator owner, I hope all is well and your search for the best brand for your pool is on track. This article will teach you how to size a salt chlorine generator properly for an in-ground pool. The process involves figuring out your pool’s volume in gallons. This process requires a little bit of math, but do not fear, we will walk you through the formulas so no one gets lost along the way. Once we have the pool’s volume set, we can decide what is the best size salt chlorine generator for our particular pool. For more information regarding converting a pool to saltwater, read our article called: The Ultimate Guide to Converting Your Pool to Saltwater

Pool Volume

Salt chlorine generators are rated for the maximum amount of gallons a salt cell can chlorinate. For example, the Pentair IntelliChlor models IC20, IC40, and IC60 are capable of chlorinating 20,000; 40,000; and 60,000 gallons respectively.

Now not all pools are rectangular, you may have an oval, round or kidney-shaped pool. For each one of these shapes there is a volume formula, and below I have listed each:

  • Rectangle – Length x Width x Average Depth x 7.5
  • Round – Diameter x Diameter x Average Depth x 5.9
  • Oval – Longest Diameter x Shortest Diameter x Average Depth x 6.7
  • Kidney – Length x Average Width x Average Depth x 7.0

For example, let us say I have an oval pool with the longest length being 36 feet and the widest width being 18 feet with an average depth of 5.5 feet. What is the volume of my pool?

Using the formula for ovals, let’s break it down:

  • Oval – Longest Diameter x Shortest Diameter x Average Depth x 6.7
  • 36 Feet x 18 Feet x 5.5 x 6.7 = 23 878.8 gallons

For the sake of having a nice round number moving forward, we will round the sum product up to 24,000 gallons of water.

Which Salt Chlorine Generator to Choose?which salt chlorine generator should I choose?

Our pool from the example is 24 000 gallons. If we were sizing our pool for an AquaRite system, we would have two choices – the AquaRite 25K and the 40K. Which is the correct choice?

The correct answer is the Crystal Pure 40K.

But Why?

Look at it this way, do you travel a further distance walking at a moderate pace or sprinting? You tire quicker the harder you push yourself and the same principle applies to your salt cell. Be kind, oversize.

If you’re a regular reader of this blog (and I hope that you are) you know that we suggest oversizing some parts of your equipment, specifically your filter, heater and your salt chlorine generator. The basic logic for each is that by oversizing the filter, you can go much longer between cleaning and by upsizing a heater you can heat your pool quicker, thereby saving money by removing the need to run your pool pump to feed your heater. And by oversizing a salt cell you allow the cell to work at a fraction of its full capacity rather than at full pace to keep up the chlorine levels. This throttling of the cell allows the cell to last longer, hopefully pushing the cell’s lifespan over the expected cell life expectancy of three to five years.

Well, that about covers it for sizing salt chlorine generators. If you have any questions about SCGs or anything else pool-related, feel free to leave a comment or give us a call at 877-372-6038.

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55 thoughts on “How to Size a Salt Chlorine Generator for My Pool

  1. I have a 13k inground pool but salt generator is 40. Does that mean i dont need to run it as long at night

  2. I have a 55000 gallon pool don’t know what kind of salt cell I need the one on it isn’t doing the job

    1. What are the actual dimensions of your pool? Length, width, and depths

      I ask because 55,000 gallons is humungous for a residential pool and it is rare to see that. So, I just want to confirm we got the right gallonage.

      1. I have a 50 by 25 ft pool with average depth of 5.5 feet. I can not find a system for my pool. Can you help

          1. Hello, I have the same question, my pool is roughly 60,000 gallon residential pool. This is a correct measurement and it is a huge pool. No one believes me until they see it. The salt chlorinator is the pentair 60k, but it is not able to keep up, are there any other chlorinator options? Or any suggestions you may have?

    2. I am looking through all of these questions and I cannot find one reply from inyopools! What good is this exercise? Lots of questions but no answers…

  3. Hello, I am about to build a 4200gal inground hot tub. Wondering what salt chlorinator/generator you would recommend.

  4. I bought the salt system for a 40K pool. It was working fine until 2 days ago, and now the LED screen is stuck on 3500 and not letting me go through the options. It also does not show that it is generating any chlorine anymore. Is there a way to reset this? I just cleaned the cell around 3 weeks ago.

  5. I have a 4k Gallon Pool (but probably only has about 3.5k gallons in it. Originally was equipped with the T-5 Cell.

    I need to replace the Cell. I am thinking of using the T-3 rated for 15k Gallons. That is about a 4x turnover rate.

    My system has revision 1.45.

    Is it logical for me to think that should still work just fine?

    1. Hopefully Joe already got his answer, but in case it helps anybody…my understanding of the AquaRite’s is that you need to have firmware higher than rev 1.5 in order to change size to something other than T-Cell-15.

  6. I bought an RJ 30 Plus Electronic Chlorine Generator system from INYO on 8-16 and finally had it installed this week. Imagine my surprise when I come back to INYO and find that they no longer offer any RJ Plus products and they don’t even offer replacement parts. The unit I purchased came with a 7 year warranty which was part of the reason I purchased it as well as the price $899.00. After reading the fine print of the “limited” warranty I see that it is effective from date of purchase so it looks like I’m more than halfway through my effective warranty before even putting it into service. Thats on me. If your looking to buy a chlorine generator from INYO i’d recommend sticking with a known manufacturer (Pentair, Hayward, etc.) and not the flavor of the season such as the current “recommendation from INYO “Custom Molded Products”, who knows where they’ll be in 4 years…………

  7. I have a 21000 gal in ground kidney shaped pool. Is the 40,000 salt generator the best one? Thank you!

  8. If I run 2 salt chlorine generator cells in parallel would I need to purchase 2 complete systems or 1 complete system w/ 1 extra salt cell? Thanks.

    1. It would depend on the make and model of the unit. Most salt chlorine generators have only one plug for a salt cell, so if you wanted a two-cell system you would need two controls. Generally, only commercial salt chlorinators have options for daisy-chaining a unit.

  9. Hey Matthew – I have a 30000 gallon pool, 2-3 people using it every other day, located in TX, can I get away installing the Hayward 25000 replacement salt cell or should I be using the 40000 gallon one?
    Also, Hayward has two options, priced about the same (see link), which one is a better option in your opinion?

    1. You need the 40K. In the article, we talk about pool size in gallons and bather load as major factors of sizing the system. Knowing you have a 30,000-gallon pool, not sure why you think the 25K is an option.

  10. I have an above ground pool with around 16,000 gallons. Does it really matter if I use an above or in ground salt water conversion kit, as long as it is around 20,000 gallons?

    1. It does not matter if you use an inground or above ground system. The main difference between the two types is the above-ground systems are usually for smaller bodies of water and the cells have adapters for flex hose plumbing.

  11. I have a oversized bathtub for a pool around 5000-7000 gal. Is their a small enough salt generator for this size that would not over chlorinate the pool?

  12. Should I install a aqua rite ? T-9
    On a indoor pool at 15000. Pool has a older gas heater with a copper heat exchanger? Thank you for your time

  13. My community pool has been remodeled in the last year with all new filtering equipment. We did not go with a salt system, just came back with a chlorine system. When I asked why not salt, I was told because our pool size has 220,000 gallons and that size is much too large for a salt system. I want to know if that information is correct, and would like to know the maximum pool size in gallons for a salt system. I think someone forgot to consider changing to salt and is possibly telling me that salt story to cover up what might be a blunder on some project manager’s part.

    1. If you scroll up a couple of comments you will see my answer to a question very similar to this, with more info. Yes, there are systems available for pools that size. Amount of cells needed is also dependent on bather load.

      1. We are currently looking into salt systems for the pool at our condo. Chlorine and chemical costs have gone up considerably in the past year. It is a very large pool and we are located in an area that has lots of sunshine and high temperatures. One of the considerations we have to take into account is the overall cost for the conversation from Chlorine to salt. In that regard can you accurately tell me the life expectancy of the salt cells and what would the life expectancy of the system be.

        1. Salt cells generally last 3 to 5 years. The lifespan of the control unit depends on the model. A simple control unit like the Intellichlor can last a few cell lifespans. A control unit like the Hayward AquaRite may need a costly Main PCB replacement a few times in its lifespan

  14. I have a question. I have a 12,000 in-ground pool. The T-5 that is sized for 20,000 says that it is for above ground pools. Is there a reason why I can’t use this T-cell for my inground pool? I’m not clear on what the difference could be…

  15. Hello I have a 168,000 gal pool with 3 pump and 3 sand filter and I am trying to find out how much chlorine I need to generate and what type of Salt cells I need. Can you assist me plz.

  16. Hi, how would you size salt chlorine generator commercial pool that’s 142000 gallons?
    Is there a formula. It seems like most of the products sold are too small.
    Would I need to buy 5 x 40,000-gallon units and install them in serie or parallel?
    What is the required salt level for a commercial pool 3500ppm or 5000ppm?

      1. Hi Matthew,
        Thanks for the quick reply. I definitely check out autopilot.

        In my country, there aren’t any local codes regarding swimming pools. So I wanted to know what are the general baseline codes for commercial pools in the U.S.

        But besides for commercial. How would you size a salt system for residential pools is it’s just based max pool volume it can handle or is it based on the system’s max chlorine production.

        Also is there a formula for calculating the amount of chlorine needs to be produced per day for a salt pool.

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