So, I wanted to make a more affordable option than the modtub especially since they are 12 weeks back ordered. They come in at about $3,000. So if you are interested in a build like this, I’m posting here to help you. Let’s get to parts and total cost.

•Grizzly 400 Cooler- $1,237 Shipped

•Grizzly Torrent Twist™ Plug with Hose Connection-$10 (add at checkout)

•Active Aqua Chiller 1/4HP (Amazon) -$600 (prices have gone up since I bought mine)

• McMaster-Carr Bulkhead- $38 side note you will need a 1-5/8” hole saw for this specific bulkhead

•1-5/8” hole Saw (Amazon) - $20

•Danner 1200 pump (Amazon)- $139

•Pentair water filter housing - $44

•Filter housing bracket(Amazon) - $13

• Filters 2pk (Amazon) - $23

•3/4” flex PVC 12ft (used 9-10ft)- $45

•3/4” fittings - $35

•3/4” pipe insulation 6ft (Lowe’s) (x2)-$18

•Oatey purple primer & pvc glue combo pack (Lowe’s) $13

•Oatey 28x30 Washing machine drip pan (Home Depot) -$31 I painted it black

Grand total: $2,266

So I saved almost $800 doing it myself along with most of these builds are on an 8 week back order. It’s up to you if $800 is worth your time.

Credit to wintermute who did this build and posted a step by step guide.

Testing out the cooler when it arrived. I’m 6’ 4” 230lbs

also side note if you want to be able to drain with a garden hose instead of taking the outlet apart you will need one of these

HD 3/4 in. Thread x Hose Nipple $1.67

Placing cooler in the garage where I want it.

All plumbed up and set up! Also, I realized the flag was backwards and as been flipped.

    So, one of the issues I ran into was that the bulkhead would leak after a day or so. After talking with a couple people. I believe it needed to be sealed with silicone on both sides of the gasket on the bulkhead. I used this loctite generously. I also noticed that the out line coming from the chiller to the return on the bulkhead was lifting up on the bulkhead so I believe it was compromising the seal of the bulkhead and creating space for it to leak. I cut the pipe down and added a sch40 90* elbow and that seemed to really take the pressure off of the bulkhead. Since doing this I haven’t had a leak. I would suggest making sure you make that line as straight as possible right off the bat to save yourself some sanity.

    What it looked like before I fixed it.

    Here is what it looks like now with the 90 added and shortened pipe

    I added this quote to the top of the cooler, just Incase my inner bitch comes out.

    Ecupirate Nicely done, and it's awesome you included links to help people! You should talk about how you drastically increased your flow rate by switching from a small filter housing to the whole home filter housing.

    The bulkhead leak is a common message that I get. I recommend sealing both sides of the gasket with silicon right from the start. Of note, multiple people have purchased silicon caulk that is not rated for use under water or in aquariums and it has failed. It could have been the product or it could have been the application. Make sure you read the product details carefully and let the silicon cure for at least 24 hours with the cooler lid open.

    For sanitation are you also just using hydrogen peroxide around 100ppm?

        wintermute I’ll definitely talk about the smaller filter that didn’t work out. As far as sanitation I follow a hydrogen peroxide excel spreadsheet that, depending on your water volume, you can shock or maintain at 100ppm.

            2 months later

            Ecupirate

            Could you upload that excel spreadsheet as a Google sheet? Or do you have another link you could suggest to figure it out? Maybe post it in the Sanitation section? Thanks!

                4 days later
                11 days later

                wintermute looks like it’s down? (Or mobile version is acting up). One interesting thing I saw with mod tub, is they remove the hinge lock and replace it with rubber grommets you can (at your own risk) put ozone through for a finished look. I think the hinge helps me feel a bit more comfortable knowing it’s not going to bonk my head.

                  a month later

                  I just built one of these an am crapping my pants on the bulkhead. My tub is outside in the elements in the North East and am wondering how could you tell the bulkhead fitting was leaking?

                  I am concerned that the water will leak into the insulation and you will never know it is happening. Then it will freeze and crack the tub

                    sannitig I'm currently in the process of building one and I think that you need to put some type of putty into the bulkhead hole to prevent water ingress. Also sealing the inside with proper silicon sealant should prevent any leaking.

                      4 days later

                      sannitig You have nothing to worry about. Even if water does get behind the bulkhead seal the only place for it to go is out the other side down the exterior of the tub. The insulation is completely water repellent and there are no gaps inside the tub walls due to the expanding nature of the foam insulation used.

                        4 months later

                        Hey are you still running a 5micron filter? I've seen people running 5, 20, all the way up to 50 and I'm concerned with how this might affect flow rate? Might be a non-issue, just curious to your thoughts.