09/22/2006
At this point, the 20 gallon frag tank next to the big tank was looking ugly. I bought a separate little 20g long tank to use for quarantine and I had some big plastic tubs to use for fragging/re-aquascaping days. I spent a lot of time on my belly on the floor staring at all the odd critters in the refugium, so I decided to turn the attached 20g into a display refugium and grow unusual algae.
So I decided to give it the spray foam treatment, and because I had a lot of askers, I documented the process as well as I could.
I do not have any holes drilled nor is there an overflow in this little tank. I had a nice SEIO powerhead to use, but I didn't want to worry about the intake getting all clogged up with algae bits. So I used a sheet of this handy plastic black grid that you can buy in craft stores or at Walmart in the crafty section. You know, it is the stuff that people cross-stitch up with yarn to make adorable little tissue box cozies.
I built it in to a corner shield where the powerheads could hide. It would keep them safe from floaties in the water and out of plain site.
I stuck it in the corner with 2-part epoxy. The fancy purple deltec kind was all I had. It's my favorite epoxy, but I would have used something cheaper for out-of-site projects, but I was too lazy for another trip to the hardware store. That pic kind of makes it look like chewing gum. lol
Then comes prepping the tank for the foamage. I cleaned the glass real well and finally wiped it down with some vinegar. Then I taped off any part that should not be stained for all eternity with black foam.
***Side note **** DO NOT GET THIS STUFF ON YOUR SKIN ****
seriously
So you start to spray in the tank. It is best to lay the tank down so that you are working with a flat surface. It does not hold very well initially and working with vertical walls is trying and it is guaranteed that you will get black foam on your arm somewhere and wear it to work for a week.
At this point, the tank reminds me of when a big flock of geese goes through your yard. It's poopy and I would never want my tank wall to look like this.
This is where is gets exciting. The foam will expand for quite a while as it cures. It will be stickier than a half-eaten lollypop and difficult to work with. If you touch it too soon, the whole mass will cling to your glove and come away from the glass.
After a few minutes, it starts to skin on the outside. This is the ideal time to start pushing the foam around a bit, running your finger slowly around on the surface to break up the poop lines and make a more regular surface.
It is also important at this time to push the foam towards the glass. As it dries and expands, it starts to pull away in places and it will create air pockets on the glass side. This is a trap for detritus, and it creates a weaker bond. This stuff is more buoyant than my fat butt in a pool, so if the bond is weak, you will most likely see it lift up, off and away as soon as you put water in the tank.
Squoosh and flatten the foam as much as possible and work out as many of the air pockets as possible.
This is ideally to give the wall some texture and interest. I recommend putting it on nice and thin. Big giant blobs will not cure in the center, they will continue to expand and make strange little foam eruptions when the center bursts out, and they will ensure that your foam floats away.
After it has had more drying time, you can take small amounts of fresh foam in your gloved hand and pat it on to the thin places or stupid looking sections.
And here is the 20 with a finished three walls of foam:
Add a little sand and some pumps and tadaaa! It is done.
What you see in that last picture is the magic that ties this tank in with the big system. Behind the tissue-cozy overflow-like thing is a very small powerhead that has tubing running to the big tank and pushes water that direction. Then, there is that "U" made out of PVC that sits in both tanks. (I foamed the visible section in the tank) You start a siphon in that U-tube, and air pressure will even out the water level to match the big tank. Powerhead pushes water over, siphon brings water back.
If the siphon breaks, the powerhead will drain the 20 a couple of inches and it ends up raising the water level in the big sump a bit.
If the powerhead is turned off, the water level in th 20 is maintained by the siphon and the salinity will go up and up and up as water evaporates and it is replaced with salt water from the big tank. It is a good idea to check the pump regularly.