As always, I start with a basic plan:

I have a loop of 1.5” (3.8 cm) pvc pipe that runs behind every stand in my fish room. PVC is so easy to use that it’s a pleasure to install it. If you can measure and use glue, you can install your own drain system. Looking at the plan I know that I need two drains for the 75 gallon tanks on the left, so I measure to locate the height of the drains and then install a tee in the system then build a drain stack to accept the hoses from the tanks. (I’ll show you the drain hose assembly from the tank to the drain later).
Here is the completed assembly that’s been secured to my wall using masonry anchors.

The 75’s have a pretty straightforward drain design. Next I have the six, 15 Gallon tanks to drain.
Their overall drain looks like this when completed and secured to the wall:

I was able to find an appropriate fitting at the local home center store that will accept the drains from the top three tanks:

I used the same fitting for the three bottom tanks, but since I have the line from above using the center drain, I had to add a tee into the system for the third tank and this makes the bottom drain assembly look slightly different from the top drain assembly:

Here’s how we get from the tank to the drain. First, drill a 1.75” hole in the tank using a quality diamond hole saw. (I’m not schilling for anyone, but I got my drill at Aquatic Eco.com for about $100)
Next, install a 1” bulkhead drain into the opening, finger tightening the fitting and then slightly snugging it with channel lock pliers. (CAREFUL) Bulkhead fittings are available in numerous places and come in various sizes. I recommend using 1” bulkhead fitting so that your drain will move enough water to make it worth your while to drill your tanks. Any smaller bulkhead than this is undersized in my opinion and not worth the trouble. After the bulkhead is in, you can attach the hose assembly that we’ll make next.
Here’s a pic of the outside of a tank with the bulkhead installed in the tank and a 90 degree barbed drain adapter placed in the end of the fitting:

Next, buy a package of flexible sump pump hose from your local home store. To complete the drain hose assembly you’ll also need a ¾” pvc coupling, a hose clamp that fits around the sump pump drain hose, and a roll of duct tape. Drain hose is assembled by inserting the ¾” coupling into the end of the sump pump hose and then tightening the hose clamp to keep it in place.
Here is this part of the assembly completed:

Next, run a thin strip of duct tape around the barbed part of the drain fitting that comes with your bulkhead assembly. This will make the drain 90 fit tightly into the coupling we installed into the drain hose earlier. Here’s a pic of the drain fitting before and after the duct tape is applied:


Once the 90 degree fitting is installed into the hose you will have a drain assembly that you can insert into the bulkhead fitting in the back of your tank.


Here is a pic of a completed drain hose that’s assembled and inserted into the drain system discussed earlier:

Even though you have your tanks on a drain system think about installing some accessory drains in your system so you can manually drain tanks, gravel wash, etc. I have these placed strategically around my room so that I have an accessory drain handy no matter where I am in the room. Here is a pic of one such drain:

There you have the basic drain plan for this one set of tanks. The process is the same for all of the other tanks/racks in my fish room. It works well, is easy to install and is relatively cheap.
NOTE: I did not include any information on drilling tanks here except to mention the bit I used. If you join the Ohio Cichlid Association, they have a great article in one of their past club bulletins that explains the drilling process. The article includes numerous photos that will help make this process easy. For info on membership: [email protected]
Enjoy,
Kyle May