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New tanks!


Staff member
Moderator (Staff)
Jul 31, 2019
Hi everyone!

I wanted to make this quick thread to document my construction of 6 new acrylic tanks that I'm going to be adding to my systems to use for water changes and to artificially increase the volume of my sumps. Hopefully this can be a good resource for anyone who wants to work with acrylic, and hopefully will answer any questions some of you may have.

I am making these 6 tanks to fit on the back of each of my systems. I need these because the sumps that I have are kind of small, and I cant pull 10% water volume off my systems without my pumps running dry. These "sidecar" tanks are going to be extra tanks that I keep running on the system, so that when I need to do water changes I can just drain them and fill them with new seawater in order to slowly drip it back into the system.

I ordered the acrylic sheets pre-fabricated from TAP plastics. I would really recommend this for larger projects. The pre-routed edges make gluing the acrylic super easy, and its was only slightly more expensive to get the sheets pre-fabbed, rather than buying the raw acrylic from McMaster-Carr and cutting and sanding the sheets myself.

I started prepping my sheets by peeling off one side of the protective paper, and lining the edges with masking tape. I do this so that once I have glued the tanks together, I can run a bead of silicone down the joints, remove the tape, and have a nice clean silicone seal in each of my joints. I also take this time to clean each of the joints that I'll be gluing together. This is a very important step to insure the joints will glue together properly. I use a towel and rub down the joints first with simple green, and then with water and then I dry them afterward. Here's a photo of the sheets once I've prepped them:

Once I finished that, I prepped the outside of each of the pieces. I could have ripped off the other side of the protective paper, but I wanted to keep it on for as long as possible to keep the tanks from getting scratched as I was building them. Because I decided to do this, I had a bit of extra work to do before I could start gluing. I peeled and cut a small strip of the remaining protective paper off the back from each side so that the joint would be clean and I wouldn't have to worry about the glue getting on and underneath the paper. A photo of this can be seen above.

Now it's time to glue! This is by far the most fussy part of the process, and also the most time consuming. Acrylic can be tough to glue together properly. Both pieces need to be flush with each other, and because I was building a rectangular tank, I needed each of my angles to be perfect 90's. If I was a bit off, the tank wouldn't fit together properly and would leak all over the place. It's time to use some right angle clamps!

Here is my clamp setup. I've got two right angle clamps on each end of the sheets. First, I glued two of the pieces together into two right angle sections, then after that cured (about 5 minutes - acrylic glue sets fast!) I glued those two pieces together into my final rectangular tank. While I was doing this, I had to be very careful that the top and bottoms of each of the separate sheets lined up with each other. If this wasn't perfect, the bottom of my tank won't glue properly and I'll be left with a leaky mess and a few hundreds of dollars of waste acrylic, not something I'm interested in.

Now that I have finished gluing all 6 of my tanks, I am going to let the glue cure overnight to ensure the joints are nice and strong, and then tomorrow I'll start working on siliconing the joints and prepping and gluing the bottoms of the tanks. I'll update this thread with my progress!


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It's been a hectic week but I have a new update on the progress of my tanks!

I have been able to finish gluing and siliconing the outside walls of each tank, I just have to glue on the bottoms now! Here's a photo!

Additionally, I built a hartford loop for each of these tanks. This nifty bit of plumbing allows me to keep a consistent level of water in each tank without having a stand pipe or some sort of complicated valve mechanism to ensure a stable water level. The water level of the tank will be equivalent to where the U in my return pipe is. The valve on the loop will remain closed during normal operation, but I can open it to drain the tank when I need to do quick and convenient water changes (the whole reason I'm working on this project). Here's a photo of the plumbing before I attached it to the tank.

And here's a finished tank! I haven't connected it to my systems yet because I'm waiting on a few more supports but once it's installed I'll post another update! You can see the other finished hartford loops in the background.
Do you have time to do a diagram on how this system works? How will you turn off the input from the main tank when you drain the aux tank?
So each of the six systems I have have a ~30 gal sump with two pumps, skimmer, filter bags, bio media etc. and one pump goes to a chiller and the other goes to a manifold that has 8 valves on it that I attach makeup lines to so I can have flow into each of my tanks (I don't have 8 tanks on every system, but I could if I wanted to). In order to do a water change with this new tank, I'll turn off the valve on the manifold that leads to this system, drain the tank using the valve on the hartford loop, and then refill the tank with seawater. Then I can turn the valve on the manifold to a slow drip in order to introduce the new seawater to the system at a slow rate.

Heres a quick drawing I made, hopefully it doesn't make things more confusing:

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