I started making my lid today following a design similar to the one in the videos posted above, but with a minor modification. I did make a few design mistakes along the way which were thankfully easy to fix. It's not finished yet, as I'm waiting for some small parts from Amazon, but here is what I have done, along with the mistakes I made, and how I fixed them.
The local glass shops were a no go. They wanted to charge me a minimum "service fee" of over $100 regardless of the size of the glass.
Obviously this was a non starter, so I just got the glass from Lowe's, and they made all the cuts for free. The only drawback is that their glass is 3/32" thick. I would have preferred 1/8" glass, but Lowe's doesn't carry it and other stores wouldn't cut the glass for me (and I definitely did not want to mess with trying to cut glass). My tank opening isn't large enough for this to be an issue, but I would very strongly suggest using 1/8" glass particularly if you are building this for anything larger than a 29 gallon (but read ahead for a caution if you do use 1/8" glass).
All the videos I saw use
this corner moulding piece to build the lid. I had two concerns. One was that the cut glass has rough edges/corners which could "catch" on the plastic while sliding. I was also concerned about the safety of handling the glass. So, I added
this J shaped moulding piece to use on the sides of the sliding glass. The idea is to allow the glass to slide more easily on top of the other plastic piece.
Here is a photo of both pieces so you can see their profiles, and a picture of how I plan to stack them:
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They are sold in 8' lengths so you can make several lids out of one piece. Or, as I would discover, this gives you a chance to mess everything up and still have enough left to start over.
Next I needed to figure out exact dimensions. My tank opening measures 11.5" front-to-back. I wanted the two pieces of glass to overlap about 1/2", which means the total width of the combined lid pieces would be around 12". For the back edge of the lid I'm using
this self-adhesive plastic weatherstripping, because it will allow me to cut openings for my filter hoses. The non-adhesive part is 30mm wide (1.18 inches) so the two glass pieces had to be: 12"-1.18" , which I rounded up to 11" (rounding up just meant I would have a slightly larger overlap of 0.68" instead of 1/2"). Instead of making two equal glass pieces of 5.5" each, I chose to make the back piece a bit larger so my light could sit completely above this piece and still be close to the center. So I made the widths 5" for the front piece and 6" for the back piece (I didn't want to make the front piece smaller than this to leave a comfortable opening for water changes).
The side-to-side dimension was trickier because it had to be more exact. The side-to side opening is 29 3/16". At the store I measured the thickness of the plastic pieces I'm using to be using just shy of 1/16". My design, as I mentioned, uses two pieces, so the total thickness of the plastic was a bit less than 2/16"on each side. That means the glass had to be 29 3/16 - 4/16 = 28 15/16 (I rounded up the plastic thickness to the full 2/16 because an error in this direction wasn't a big deal, but an error in the other direction would mean the glass wouldn't fit). So I had Lowe's cut the two pieces as 28 15/16" x 6" and 28 15/16" x 5".
The first thing I did was to sand the edge of the glass to make it safe to handle. I used a 120 grit sanding sponge (
like this one). If you do this, wear a mask, safety glasses and gloves. The glass IS sharp from the cut, and sanding produces very fine glass dust you don't want on your eyes or lungs! Thanks to COVID I had masks at home.
I then used krylon fusion spray paint to paint the pieces black, which is the color of my tank frame. I figured I'd paint them before cutting, which was a mistake. All the handling I did to cut the pieces afterwards scratched the paint. So first lesson: cut first, paint later. But read ahead
before you paint anything, because painting the pieces turned out to be another mistake.
I cut the pieces to the right lengths (using pruning shears!) and then assembled the moving section of the lid:
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The 3/32 glass fits nicely in the opening of the plastic pieces, but not snugly. It works well, but for added safety I will silicone the piece in place before I'm finished (
CAUTION if you do this with 1/8" glass: the groove in the "J" shaped piece is narrower than the groove in the other piece. Check at the store to make sure the glass fits in the groove of the "J" piece, it might not! They do sell J shaped pieces with wider grooves).
Here is a detail view of how the glass fits in the groove:
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Then I placed the whole assembly on the tank. Even though the fit isn't snug, the whole thing is quite stable. Still, I'll feel much better once everything is siliconed in place (this is my old tank, which is why it's painted black
):
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And here is when I realized my design had a significant flaw. The paint on the plastic pieces makes them stick to each other so they do not glide easily at all. I realized that the two surfaces of the plastic that slide against each other cannot be painted if they are to slide freely. Luckily I have plenty of plastic left so I cut new pieces, and this time I used them without paint:
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Now they slide quite easily! Tomorrow I will paint the pieces, but covering the surfaces that slide against other with tape so they remain paint-free. It means that if you look at the tank from the top you will see the white plastic of the bottom piece, but since the lid of my tank sits slightly above eye level, nobody will be able to see this. If your tank is acrylic or frameless you can just leave them white.
One drawback of using the two pieces of plastic this way is that it makes the gap between the two glass pieces wider. There is a gap of 3/16" between both panes. Probably not a big deal, bit I will use
something like this to cover it. I will stick it to the bottom piece of glass at the front edge to "seal" the gap.
I will wait until I get the weatherstripping from Amazon to silicone everything in place and finish the lid.
One note: an advantage of the loose fit between the glass and the plastic is that the glass piece inside the groove (i.e. the bottom piece, which I placed in the back) slides very easily inside the groove. You could make the bottom piece the one that slides (i.e. make it the front piece) and put the top piece in the back, fixed. I was going to try this but it creates 3 problems: first, if you do this you won't be able to use the second piece of plastic (the"J" shaped piece) and the glass could "catch" on the plastic as it slides. Second, It would be impossible to remove the front piece without removing the entire lid. Third, and most important, if the bottom piece is the one that slides, the handle on the lid would prevent that bottom piece from sliding all the way back, and the opening would be narrower this way. If the sliding glass is on top you can slide it all the way back and have a bigger opening.
Once I receive the weatherstripping from Amazon I will post the finished product!