Corner Plywood Tank

[Crwhite]

Hey there, new enthusiast here with lots of excitement for building a new plywood tank. Not necessarily monster sized, but from what I have read in the last few weeks online, this forum seemed to have the best advice and experience in building plywood tanks.

I built my tank over the weekend and it is currently 36" out from the 90 degree corner on each side, and roughly 51" across the front (hypotenuse.) Rough volume is calculated to be +/- 84 gallons. Photo below shows the intended cutout area for 1/2" glass.

Here is where I need some expertise;

I have access to a polyurea product that is used for potable water tanks, which I am hoping to have our tech spray into my tank to waterproof it. However, I am unsure how to seal that coating to the glass on the inside of the tank.

My thoughts are to use an aquarium safe silicone, such as the RTV108 and seal the plywood to the front wall before the tank is sprayed, and let it cure for a few days.Our tech tells me that this polyurea will stick to almost anything, provided that proper prep is done, which would involve buffing up the outer 3" or so of the glass, and then priming it along with the rest of the tank interior before blasting. I will then mask off the inside of the glass just past the viewing area and have our tech blast the entire interior with grey polyurea coating, ideally to 80-90 mils, just to be sure we get everything coated. I'm curious what you guys would use for the edge of the polyurea coating on the glass. Would you use the RTV108 there as well? I'm curious if anyone has used this method before... I know that normally this might be very expensive, but we are trying to use up the grey here at work, so I am able to get it for a nominal price.

My next question is if I should have is in regards to the bulkhead fittings/cutouts I will be putting in this tank. Being a corner tank, I would like to have everything running up from the bottom of the aquarium... Would you put the fittings in before this is sprayed and just mask them off? Or am I better off to cut them out after, and seal against them with the rubber crush washers?

I look forward to any insight you guys might have into this process, as there is obviously a wealth of experience in "the room."

For anyone interested, I will be putting multi flourescent sevrum in the tank.

Thanks in advance for all your insight and wisdom.

-CR

 

[Crwhite]

Just thought I would throw up an update here showing current status of the project. Enjoy the pics!

Quick rundown of the photos is as follows (as I couldn't figure out how to embed them, maybe next time...

First 2 pics are of the tank propped up in place with the cutout for the glass.

Third photo is the tank sitting on the stand that I build.

Fourth photo is the tank with the glass installed. (This was a real pain in the butt. I should have taken into consideration how much interior room I was loosing with the design, but it worked...)

Fifth and sixth photos are the glass installed and extra silicone cleaned off...

Seventh and eighth photos are of the bulkheads and wier mocked up in place.

Nine is the sump tank I built (black aquarium silicone makes this look rather unaesthetically pleasing, but it's hidden so I'm ok with that...

Ten through thirteen are the tank in various stages of prep for polyurea.

Fourteen is the painted wier.

Fifteen is the sump system I am using (5 gallon pail style trickly tower) and cartridge style filter.

Sixteen is the sprayed tank in the back of the truck on the way home!

Seventeen is the sprayed tank placed on the stand.

Eighteen is a shot of the plumbing and everything mocked up into place to see how it will fit. I am very pleased with this...

Nineteen is the tank with a cheap light (not to be used for the tank, just needed something to light up the inside for photos and to clean the glass.

Twenty is with the tank in place and couch pushed back. and overflow/return loosely fitted into place.

I'm going to let the polyurea cure for a few days (it's dry to the touch within minutes of spraying, but I want to give it some time to gas off...) Then I will take it back outside and do a water test. Just wanted to get it mocked up in place to see how it will look.

I am very happy with the build so far, and I welcome and comments/critique that you can offer.

Thanks!

-CR

 

[takagari]

Did you spray paint the inside of the tank over the sealant?

 

[Fish Tank Travis]

Looks like a nice and unique build!

 

[Crwhite]

Did you spray paint the inside of the tank over the sealant?

Hi Takagari,
No I did not spray paint over the sealant. I am leaving the polyurea coating the same color it comes out as. It sparkles somewhat under the light which I really like.

 

[Crwhite]

Looks like a nice and unique build!

Thanks Travis! Its starting to come together.

 

[convict360]

That is an awesome build, I also want your couch it looks like a throne lol

 

[Crwhite]

That is an awesome build, I also want your couch it looks like a throne lol

Thanks convict360, I too enjoy my couch. ;-) I even built my tank stand so that the chair can still recline below the support (I will box this in as I complete the project.)

 

[theokie]

I'm glad you adhered your glass to the wood and then appied the polyuera. I work as a NACE II coating inspector for a a polyurea company, and on a recent project they had bubbles coming through the product and opted to attempt a repair with off the shelf silicon. Lets just say that there was no adhesion between cured polyurea and the silicon.

As for adhesion to glass I'm pretty sure you will have an adequate seal, since you did rough up the surface prior to application. We have never sprayed glass so I really have no data on it, but I don't see why you wouldn't get a decent bond. Its not like when they sprayed polyethylene and wondered why it just peeled right off in one big piece.

I am watching your thread as I have considered doing a plywood setup with the polyuerea as application is so easy with a plural system, though do to the silicon window issue I opted a 100 % solids epoxy for my first test tank.

Keep us updated

 

[Crwhite]

I'm glad you adhered your glass to the wood and then appied the polyuera. I work as a NACE II coating inspector for a a polyurea company, and on a recent project they had bubbles coming through the product and opted to attempt a repair with off the shelf silicon. Lets just say that there was no adhesion between cured polyurea and the silicon.

As for adhesion to glass I'm pretty sure you will have an adequate seal, since you did rough up the surface prior to application. We have never sprayed glass so I really have no data on it, but I don't see why you wouldn't get a decent bond. Its not like when they sprayed polyethylene and wondered why it just peeled right off in one big piece.

I am watching your thread as I have considered doing a plywood setup with the polyuerea as application is so easy with a plural system, though do to the silicon window issue I opted a 100 % solids epoxy for my first test tank.

Keep us updated

Hey Theokie,

So I've been quiet the past few days as I went to leak test the tank it it failed and I've been working on finding/researching my way to a solution. The coating (including primer) is pulling away from the glass. Apparently sanding the glass with 40 grit sandpaper wasn't enough prep. ;-(

As mentioned above, silicone won't be a fix, as it wont adhere to the polyurea so I have been researching some other products... I work for a manufacturing company and we have numerous products at my disposal to use, and I have one product in particular that I am looking at for making this very important seal. It's 3M's 550 Fast Cure polyurethane adhesive sealant. Does anyone have any experience with this product with fish? I used this beneath the polyurea to fillet all the corners and around the fittings at the bottom before we primed the tank, and it is very nice to work with.

http://solutions.3m.com/wps/portal/...ridge-12-per-case?N=5510818+3292835715&rt=rud

Fortunately with my job, I do have access to some reps at 3M so I am trying to figure out if this would be a safe product, once cured.
I've also heard of various other people using 3M 5200 Fast Cure Marine Adhesive Sealant with success in their tanks.

I'm looking for some feedback on either of these products, as I'm reading mixed reviews online as to what constitutes a safe product, as some of the ingredients used in the polyurethane products are dissipated as the product gasses off.

I've been learning a tonne from this forum, and appreciate any insight and wisdom that you can send my way.

Talk soon!

-CR