How To Decide Whether You Need An In-line or Off-line Chlorinator


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One of the main questions customers ask when they are deciding to buy a chlorinator is, “How do I decide if I need an inline or an offline chlorinator?” Well, chlorinators play an essential role in keeping your pool healthy for your family. However, not all chlorinators were created equal. You need to consider the best option for your pool and family.

Step by Step


Step 1

What type of pool do you have? Determining whether the chlorinator is for an above ground or in-ground pool will greatly narrow your search.

Step 2

Determine the size of your pool. Calculating the number of gallons your pool holds will factor in when choosing how big or small your chlorinator needs to be in order to keep your pool healthy. Click here to determine the number of gallons in your pool

Step 3

Brand- Do you your research. Bigger names are slightly easier to maintain for the simple fact that it is easier to find replacement parts if necessary, as opposed to having to replace the entire chlorinator. Also, check to see if the chlorinator comes with any additional features such as the self- cleaning option.

Step 4

Next, you will need to decide whether you need an in-line or off-line chlorinator. It simply comes down to the question of whether or not you have room to place the chlorinator in-line with the rest of your equipment. In-line chlorinators are connected directly after the filter (or heater, if you have one) and should be the last piece of equipment before the water is returned back to the pool.

Step 5

Off-line chlorinators are typically used when an in-line chlorinator cannot fit into the existing system. The off-line chlorinator is connected through a bypass line off-line from the rest of the equipment.

Step 6

Don't forget to check the chlorinator capacity. Ensure the size of the chlorinator you chose is sufficient for your gallon size pool.


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 Posted: 10/23/2018 

Do you suggest the Rainbow 320 chlorinator or the Hayward CL200 Chlorinator?

InyoPools Product Specialist  Posted: 10/23/2018 

Hello Patrick - I would recommend the Rainbow 320 over the Hayward CL200 chlorinator. The lid on the Hayward chlorinator becomes very hard to remove. The reason for this is that the o-ring expands and makes it very difficult to remove the lid. The Rainbow 320 does not have that problem.

InyoPools Product Specialist  Posted: 10/23/2018 

I would suggest the Rainbow 320 chloorinator as where the pipe connects underneath the chlorinator is 2" in diameter where the Hayward CL200 reduces to about 3/4" which really restricts water flow and increases pressure in your system.

Anonymous  Posted: 10/23/2018 

Please post the link to the Rainbow 320 chlorinator so I may purchase this chlorinator.

InyoPools Product Specialist  Posted: 10/23/2018 

Here you may view the Rainbow 320 Chlorinator.

InyoPools Product Specialist  Posted: 7/17/2017 

Anonymous (chlorinator) - The standard Rainbow 320 Inline Chlorinator will work well for your size pool.

Anonymous  Posted: 7/13/2017 

Hi. I have enough pump house room to fit an inline chlorinator but I am not sure of the size I require. Our pool will be 10.7m x 4.2m with a sloping bottom. Shallow end is 1.0m & deep end is 2m. I am looking at the Rainbow feeders. Can you tell me which one I should select please. Thank you.

InyoPools Product Specialist  Posted: 2/28/2017 

Chlorinator - Many people use the Rainbow 320 Inline Chlorinator for your size pool.

Anonymous  Posted: 2/28/2017 

We can use a in-line chlorinator (3" tabs). Our pool is in ground about 9000 gal what size do I need?

 Posted: 1/12/2017 

Nicely done but when running the spa and pool returns at the same time you'd be heating your pool water. Is this the set up most people use?


InyoPools Product Specialist  Posted: 1/19/2016 

Rpswat - For your size pool I would recommend a high capacity chlorinator like the Rainbow HC-3315 High Capacity Auto Feeder. It will treat a pool with up to 97,600 gallons of water. This size gives you the capability to super chlorinate during heavy use in hot weather.

 Posted: 1/15/2016 

What options are available to add a chlorinator to a 56,000 gal pool?