Sealing and Drilling a Tank

[Neon Reefer]

As you guys know I am a DIY guy and since I am rebuilding a 150G right now I thought I would share some process on sealing and drilling a used tank.

1.)Sealing the tank

Place tank on the work bench and proceeded to scrape out the existing silicon down to the bare glass to include utilizing acetone to remove the silicon between the glass panels. Using a box cutter and a razor scraper, layers of old silicon are removed by 1st scraping the silicon from edge to seam with a razor blade and then cutting at the seam with a box cutter. Pulling will then remove the bulk of old silicon and then rubbing with the acetone will remove and soften remaining residue. The box cutter is also used to remove the silicon from between the panels. This was done 4X until there was only bare glass and no old silicon residue. New silicon will only bond well with glass and not so well to old silicon. The most important thing to remember when resealing a tank is the glass must be very clean. Now it is time to tape up the tank in preparation to laying down the new silicon. I used frog style painters tape for this job placing nice straight lines of tape with a ½ wide gap for new seams. Just like painting, the quality of resealing the tank comes in the prep done prior to laying down the silicon. Laying down the silicon is pretty easy using my Ryobi electric caulking gun. I use GE Pure Silicon I Clear and set my gun to medium and laid down a continuous bead about the size of a triple A battery, only stopping momentarily to change the tube of silicon when empty. As said laying down the silicon is easy but must be done quickly as you only have about 5 minutes to get it done and start pulling the tape before the silicon starts to crust on the tape. So after quickly laying the bead of silicon down and running my gloved finger along each seam in a single pass to flatten the silicon along the seam and to force into the seam, I also began carefully pulling the tape. Nothing left to do but let it cure for 5 days. This whole process from beginning to end, scrapping to caulking on this size tank requires about 10 hours labor. On Thursday after work I filled the tank and dusted with powder to look for any leaks. Left tank filled three days. The following Sunday I was ready to drill the tank.

2.) Drilling the tank

Prepping for the drilling process

The first thing is to determine if the tank has any or all tempered panels. Tempered panels cannot be drilled. The best way to do this is to call the manufacturer with information about the tank. All tanks have a sticker somewhere on them with a code and a date. This information along with the dimensions of the tank is all that is needed for the technical or engineering department of the manufacturer to tell you if some or all the panels are tempered. I located the sticker under the left side front top frame recorded the information and called Marineland and got an engineer on the phone who was happy to look up the information for me. Good news as no panels on this tank were tempered. He also said in most cases on large tanks any glass over 10mm is rarely tempered. With this in hand I still used the layman way to tell is glass is tempered. In an area of low ambient light place a polarized light source behind the glass. This can be any LED screen such as a laptop or a smart phone. Then look thru a pair of polarized sun glasses. If all you see is a regular screen then no tempered glass. But if you see distortions normally looking like black or gray bars running across the picture then it is tempered glass. Great news I saw no distortions. I would also check the results out by looking thru the side glass of a newer model automobile with the light source and the sunglasses. You should see distortions as all newer model cars have tempered side glass pane Then you check your tank. Next determine the size of the hole wanted to fit any particular bulkhead you want to utilize. Remember bulkheads are listed in size by the passage size thru the bulkhead and the fitting that can be screwed into it. The hole needed to install the bulkhead will be significantly larger than the size of the bulkhead and is normally noted in millimeters. IE my 1 ½ bulkhead required a 60mm hole. Not all same sized bulk heads will require the same size hole, so be sure to know before you drill. In my case I want to install the new H2Overflow and anti-siphon returns so I purchased the entire kit including the two diamond coated boring bits and a template to determine exactly where to drill.

Drilling

First determine where you need to drill. A couple of simple guidelines is try to never drill closer to a seam than 2 and try to never drill two or more holes closer than 3. And only drill as many holes as absolutely needed. The more you drill the more you weaken the integrity of the glass. The only reason we can drill our tanks is because the glass is grossly over engineered in the first place. Holes closer to the top weaken the structure less than holes drilled in the bottom where the bulk of the weight is located. Buy or build a jig to guide you thru the process this is done utilizing a small square or rectangle of ¾ plywood. Measure the holes from the frame or if frameless from the edge of glass from two directions if in a corner and one direction if not a corner and transfer onto the plywood measuring exactly the same. Then drill with a hole saw to the same dimensions as the diamond hole saw. Next cut a small V shape with the smaller end of the V opening into the hole. This will allow you to place a water source on the bit while drilling. Now firmly attach the jig in place to the tank with bar clamps or with the clear packing tape used in dispensers. Note if using the packing tape be sure to wet the glass first as his stuff is really hard to peel off glass. The water gives it just enough damping to stick but yet peel off easily. Just make sure the jig is firmly in place. Take your diamond hole saw and place into the jig. Using a marker mark the hole saw at the top of jig. Take out the saw and now measure from the line on blade towards the stem of saw the exact number of mms the glass you are drilling and make another mark all the way around the blade. This way when you are drilling and this line approaches the top of jig you will know when to slow down and ease up on the drill as not to chip out the back of glass. Next apply the water source using a garden house clamped or taped in place where the water flows into the V and hole in your jig. Place the drill in the jig and with a cordless drill (Do not use a corded drill and a water source together as this is an electrocution hazard.) Place the drill on high mode and begin drilling with only the force of the weight of the drill. Once the drill water begins to produce a little white color you can slowly rock the drill ever so slightly will leaving the weight only of the drill as pressure. You will see more white material in the water falling from the jig. This is an indication it is moving thru the glass. As the line on the bit approaches the top of the jig stop rocking and make sure the drill is in perpendicular alignment to the glass so the drill will go thru the glass evenly and prevent a chipping out of glass on the back side. I prefer two things when I drill. I like to drill in a downward position instead of drilling in front of me and I like to drill from the side where the gasket is going to go. So some applications will require drilling from the inside of the tank and some from the outside of the tank. It takes approximately 3 minutes of continuous drilling time to drill a hole in 10 mm glass once started. A bit will cost approximately $20 and is only good for 3 5 holes depending on thickness of glass. Since Im drilling 12 mm glass my bit would be good for three holes. And once you are thru drilling DO NOT run your finger in the hole to check it, as glass holes their cut outs and shavings are frequently sharp. Use fine grit sandpaper to smooth the edge of the cut if needed. Upon inspection a small amount of chip out is normal and will not affect your sealing with the bulkhead. If there is significant chip out then use some silicon when applying the bulk head. Some do this anyway.

This information and more with pictures will be available on my new build thread coming soon.