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

WRITTEN BY:  Inyo Pools

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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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Inyopools  Posted: 07/17/2017 10:53 AM  Inyo Product Specialist

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

Anonymous  Posted: 07/13/2017 16:24 PM 

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  Posted: 02/28/2017 14:21 PM  Inyo Product Specialist

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

Anonymous  Posted: 02/28/2017 13:12 PM 

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

david  Posted: 01/12/2017 1:41 AM 

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  Posted: 01/19/2016 10:21 AM  Inyo Product Specialist

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.

Rpswat  Posted: 01/15/2016 20:15 PM 

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