Bonding aragonite to acrylic

Does anyone know what I can use to bond aragonite to acrylic? I'm trying another scrubber concept.

 

What type of two part epoxy would be reef safe?

 

Thanks Turbo. I remember a couple years ago, I was trying to find that info out on SM's site. I had then posted an AS wheel concept photo and remember you (and I think Garf) trying to help me. Life happened and I was forced to postpone my project. Finally, I completed my new aquarium build after 4 1/2 years. What a feat! After devoting over 2000 hours and investing >$13K I was able to try that wheel for the first time. I initially tried scuffing the wheel and the acrylic overflow lip with sand paper, applied a generous layer of silicone and then covered it with aragonite. The result, the aragonite kept falling off. This sparked some new ideas and now I'm back to the drawing board on my AS concepts. I'll gather up the pix of the previous attempt and post em this weekend. I'd like to get your input.

 

This is the pic I posted a couple years ago.


Most recently, this is where I tried to bond the aragonite to the wheel and acrylic with aquarium silicone. I was aware that silicone didn't bond well to acrylic so I sanded it pretty well and chanced it. And, as previously stated the aragonite just wouldn't stick to the silicone. I didn't have much of an issue with the silicone adhering to the acrylic or the wheel. What do ya think? One other problem I had was that the wheel just wouldn't turn enough. At times it would spin (but slowly) and other times it'd sit still. I imagine the water was running through the wheel and just not creating enough friction to turn it. Now I'm trying to figure out how to incorporate paddles to force the wheel to turn.

 

I would try adding the substrate into the epoxy mix and casting or pressing into a mold. (http://mold-making.com/imitation_sandstone.htm) Might take some trial and error to get the right ratio of sand to epoxy.

The head of a nylon screw could be placed in the mold so that the threaded part remains exposed in order to mount to the acrylic. Epoxy doesn’t typically bond to nylon so a hex head bolt would be best to prevent it from spinning once the epoxy cures. Something similar could be done with pieces of acrylic encased in the mold. Holes or protrusions in the acrylic for the epoxy to encapsulate would provide more of a mechanical locked-in-place attachment rather than an adhesive bond to the acrylic. The exposed acrylic could then be glued as normal.

 

Thanks for the 'mold' tip mulcmu! I may use that as an alternate course of action if Turbo's 2 part epoxy suggestion doesn't work.

 

I like this wheel design, it reminds me of some commercial scrubbers I've seen. The difficulty like you say though, is getting the wheel to spin reliably, both when the screen is bare, and when it's full of algae. There's a risk that the algae may start to grow initially or predominantly only on one side, and if that happens, the screen will probably stop spinning. I'm not sure if there is an easy way around that when using a water pump. You could try submerging most/all of the screen under the water line, having fins on one side, and having an air pump push bubbles into the fins, which will in theory move the wheel. As the growth on the screen increases, the air bubbles would build up until they had enough pressure to keep the screen rotating. You'd probably need fairly large fins, and ideally a water pump pushing water through the housing, but I think it would work well.

 

Thanks! I personally had never seen a design like this before. I came up with the concept a couple years ago. I had been researching scrubbers for a bout 6 months previously. I'd be interested to see a photo of the commercial ones you spoke of.

I'm going to see if I can cut in vanes or fins in my end caps on the wheel and see if the run-off from the lip will turn it. My waterline sits about 1/4" below the filter sponge just underneath the wheel. So, submersing it doesn't seem like much of an option for me. I think I will try to run fins on the inside of the wheel screen as well. That way as the water pours through the wheel screen it will fill in between the fins weighting it and forcing it to turn. And if that doesn't work I may just remove the wheel and make a flat angle plate with rakers like the one pictured above but extends all the way down to the filter sponge if the wheel option doesn't produce results after I put in the fins.

 

Ok, so I spent some time in the garage with a cigar and scotch and this is what I came up with... I had to make the fins internal because I didn't have enough space around the circumference of the wheel.


The internal fins actually worked! I'll post the video as soon as I figure out how to do that...

 

This is where I'm at so far. Still have to bond the aragonite onto the acrylic lip...

 

Looks pretty sweet.
Was this just for test purposes? How will it continue to spin when there's the sand mixture, or algae growing, on the surface of the screen?

 

Yes, it was a test run. I wanted to see how well the internal fins would work. I think it turns quite well actually. The fins added a bit of weight though. I don't think I'm going to add sand to the wheel now, only the overflow lip. I'll try scuffing up the wheel instead. How do you go about that? What do you use to rough it up?

 

I use a hole saw, works fine for me.

 

Interesting concept. I wonder if you had a cylinder support for the screen and fins sticking out through the screen that would work if you get what I mean?