My DIY lid
Alright kids, so to refresh everyone's memory, I needed to construct a top for my Cad 39g Pro to keep my new bluespot jawfish, JAWS, from carpet-surfing. My goals/requirements for the lid were, in order:
1) no carpet-surfing jawfish, so I had to keep the holes no bigger than 1/4" (3/8" might've been ok, but I was happier with the 1/4" threshold).
2) allow for as much evaporative cooling as possible to keep my tank temperatures at a reasonable level, because I will be suicidal if I end up having to waste money on a chiller. However, I am wary of using plastic mesh/pond netting because I do not want it to melt under the halide, which is positioned 3" above the top of my glass and 4" above my water line. I cannot use galvanized metal because of the zinc content, which I understand is problematic for inverts.
3) minimize lost par as best I can, especially from the halide, but with the understanding that the above two requirements have to take precedence.
As an aside, it's a very good thing I built this -- the first night we had Jaws, my wife and I woke up hearing splashing and a "thump" against the top as Jaws attempted his first escape. However, the top held him in, and he lives to screw up my sandbed another day!
Now, on to the project:
First, I bought a piece of light diffuser/eggcrate from Lowe's. The holes in it are about 1/2", and they are decidedly wider than even a fully-grown jawfish body. However, I address this issue later. Before I do anything, I remove the lights and use scissors to snip the eggcrate roughly to the size of the tank from left-to-right. I line up the corner of the eggcrate with the left back "outside" corner of the tank and then straight back on the right side (you can, of course, do it the other way - this was just easier for me), being sure to cut it to size at the outside of the glass so that it fits securely on top of the tank.
Next, I need to make notches in the eggcrate to accomodate the "feet" of the fan over my overflow. First, I line up the corners again, and I then take a marker and mark to the outside of the feet, being careful to cut as little as possible so that there no jawfish "escape hatches." I cut one square deep into the eggcrate, which is about perfect for the fan feet. This really helps with keeping the lid in place and precisely on top of the tank. Note that I could also have cut out spots for the light "feet," but I decided against it, since the lights will help hold the top in place and counter-balance the weight of the glass in the middle. it also lifts the light off the glass/water a little bit more, so hopefully that will help with temperatures (I can't imagine it will matter much, though).
Next, I have purchased an 11x14" piece of glass for a picture frame from a crafts store, which I am going to use directly underneath the halide to 1) help minimize lost par from the use of the eggcrate and 2) get the plastic out from underneath the halide (although I am not as worried about eggcrate melting as I am about pond netting). The eggcrate will serve as a "table" support for the glass around the edges (which is why I bought 11x14 when I would only realistically need 8x10 to accommodate the halide). So, I need to cut a hole in the middle of the eggcrate for the glass. I do this by sliding the eggcrate into place on top of the tank, placing the light on top of the eggcrate, centering (roughly) the glass beneath the halide.
side view:
I then measured 2 squares (on the eggcrate) in toward the center at each corner of the glass (so, e.g., as you look at it from the front, I measured 2 squares down from the top left corner, then 2 squares right from the top left corner, and marked that point on the eggcrate. I then began cutting away the eggcrate within these 4 points. Here's what it looks like with the glass hole fully cut-out. I wound up cutting one additional square around the hole, to allow more light from the actinics, but it also lessens the amount of support for the glass, so that's just an option:
Next, I have to cut the eggcrate to the curve of the front of the tank. First I mark it, which I do by simply sticking the eggcrate on top and sliding it straight back into the fan foot holes. At that point, it should be even on the three already-measured sides (and if it's not, you can mark more to trim off). I then make a mark on the bottom of the eggcrate by sliding the marker along the front of the glass like a stencil. I then remove the top and take a dremel with a "sanding disc" (I don't know what these are actually called), and cut along the line that I've drawn as best I can. This will not be perfect, but we cover it up later, so it's ok if it's not. In addition to shaping the front of the lid at this time, I also made a small cover for the overflow out of the leftover eggcrate. This serves as both additional support for the lid and to keep fish out of the overflow. I simply cut the eggcrate to roughly overlap the length/width of the overflow, that's it. Then, I set the lid on top of that.
Now for my secret weapon against jawfish surfing: fiberglass window mesh. I bought a roll of this from Lowe's, rolled it out on top of the eggcrate, and cut it so that it overlapped about 2" on all sides (roughly). I then folded up the back corners around the eggcrate, creating a sort of "coating" around the edges, and sewed them in place. I then roughly folded the mesh along the curved front half and sewed it in place at the front corners and once in the middle. This looks better than it sounds, although there were probably better options than sewing -- but it was getting late and both I and Jaws were getting antsy by this point. I then cut out holes in the mesh where the glass will go and where the fan's feet will go.
So, I then slide the lid back on top of the tank, stick the glass piece in place, remount the lights, and voila, I'm done!
