Phixer wrote:Viktor, did you ever get the information you wanted regarding aquarium construction? The sealant you were looking for to seal the acrylic viewing windows to the frame is Dow 795. I normally build tanks over 1000 gallons and might be able to answer any questions you may have. I probably wont check the message board very often so feel free to email me if you or anyone else would like to know how its done.
Hi Phixer! Thanks much for your post and the info! No, IDK what this sealant is and I will read up on it. So, you are saying you use it to seal what to what? Acrylic pane to raw concrete or sealed concrete... or sealed wood or rubber liner, or fiberglass, or stainless steel, etc.? Plus the concrete and wood sealants are many and vary greatly in their properties... And what about glass panes?
For now I have just gone with ten 240 gal glass tanks from GlassCages and with two 4500 gal fiberglass tanks with 8'x4'x2.5" acrylic windows made by Dolphin Fiberglass out of Homestead, FL. Have not dared yet to make my own exhibit, except for a koi pond. Have not had the time anyway.
I have been mulling over a 25'x25'x8' exhibit, EPDM rubber liner with glass or acrylic windows as a next-step project. Just afraid to have problems down the road as we are a 1.0-1.5 man show. Some things better be outsourced, if at all possible. If I start having leaking tanks, I'd struggle much with the rest of the duties to keep the place going. And I am in no position to throw money at problems. Our Aquarium and Fish Rescue is a "DIY" kind of a venture. My wife and I are doing it all on what we have saved together, having no sponsors, no borrowing, no mortgage, no business loans, etc.
Do you do things like that for hire? I mean you'd lead and I'd help and learn along, as one option, if it was affordable to me.
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Hi Viktor. Dow 795 can be used to seal the acrylic panels directly to the concrete or fiberglass. In other words, a bead of it is applied around the perimeter of the acrylic window and the window is pressed into place in the same manner plywood tanks are made. I used to live in San Diego and would visit the Scripps Institute of Oceanography on the weekends, I studied their tanks closely and spoke with them on many occasions, this is how their tanks are sealed. All are made using acrylic windows and Dow 795 sealant.
I would use fiberglass or concrete tanks with acrylic windows. The tanks at Scripps are both, all are coated with a swimming pool marine epoxy on the inside. UV light, however, will make this coating brittle over time.
How will you be supporting the weight of the viewing windows? If you can try not to have the weight of the window supported by the sealant. Use acrylic blocks at the base of the window to support the weight. The hydrostatic pressure of the water will create a water tight seal. The acrylic will cost a little more up front but if the aquariums will be open to the public acrylic is much safer as it will not fail catastrophically like glass.
If you were to build this way I think you would have minimal if any leaks.
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Hi Sam! Thank you for the info!
S: Dow 795 can be used to seal the acrylic panels directly to the concrete or fiberglass. In other words a bead of it is applied around the perimeter of the acrylic window and the window is pressed into place in the same manner plywood tanks are made.
V: I thought that usually the window is sealed against a surface that's already coated=sealed with a waterproof coating, eliminating the crack between the window sealant and the waterproof coating of the wall. In other words, there is an overlap of waterproofed surfaces. So, I must surmise that you are saying that Dow 795 is placed between a clean acrylic window and a coated wall, not raw concrete, fiberglass, or any other raw non-waterproof material, right?
S: I would use fiberglass or concrete tanks with acrylic windows. The tanks at Scripps are both, all are coated with a swimming pool marine epoxy on the inside. UV light, however, will make this coating brittle over time.
V: Good to know. So, Dow 795 will be in contact with this marine epoxy, not concrete or fiberglass...... On concrete: some professional aquaria builders professed to me in my conversations with them that a concrete tank cannot be sealed so that it does not leak. The most it will last is a year or so and then the water will start seeping through. That's why I was thinking liner, as in e.g. air | tank structural wall | rubber liner | concrete (to protect and hide the liner) | water - that type of a cross-section.
S: How will you be supporting the weight of the viewing windows? If you can try not to have the weight of the window supported by the sealant. Use acrylic blocks at the base of the window to support the weight. The hydrostatic pressure of the water will create a water tight seal.
V: There'd be a window sill. Or a stainless steel frame that would hold the rubber liner and the window (with a sealant in between them if one is needed) together. No, I'd never let the window hang on the sealant - that'd be a shady construction.
S: The acrylic will cost a little more up front but if the aquariums will be open to the public acrylic is much safer as it will not fail catastrophically like glass.
V: True but the price difference is not a little, I'd think... from the little that I know. 1.5 years ago when my 4500 tanks have been made, I paid $8000 per each 8'x4'x2.5" acrylic sheet. Nowadays, it is significantly more expensive and it keeps climbing like 10x more steeply than an average inflation rate. I have not priced a comparably strong piece of glass (I understand it will be much, much heavier too). Are you able to provide a point of comparison for a sheet of this or comparable size?
S: If you were to build this way I think you would have minimal if any leaks.
V: Is it normal for a Public Aquarium tanks to have minimal (what's that? a mL a day? a gallon an hour?), or non-zero leaks? I thought they build so as to have no leaks whatsoever, for a long period at least.
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Hi Viktor, ... In no particular order here... It would be hard to tell if a concrete swimming pool is leaking or if the reduction in water quantity is due to evaporation. How would one quantify or verify this unless the leak was pretty bad and one could see it with dye. I can see that due to the size of a swimming pool cracks may happen over time and the water may leak out from there. Leaks in any amount should never be accepted for aquaria kept indoors though. Materials such as Blue Max remain flexible to my understanding and would seal all but the largest cracks, polyurea also, I’m not sure what material or size concrete pool they are working with. UV, Chlorine and ozone will degrade most sealants over time though.
Yes, depending how you build your tanks fiberglass or concrete, Dow 795 will stick to acrylic and marine epoxy, I'm not sure about the liquid rubber stuff if you choose to go that route. If you are using a fiberglass or concrete tank with a marine epoxy top coat, Dow 795 will adhere fine to it and the acrylic, in addition to the pressure of the water pushing against it will create a good seal. Be advised though, when you perform water changes you lower the water level and this will reduce the amount of hydrostatic pressure on the panel. Theoretically over time this process of pressure fluctuation may weaken the seal.
Holy cow Viktor!
they charged you 8K per sheet for 4x8ft 2.5" material? I hope you make a note never to use that vendor again.
(VJ EDIT: This is what I was told by the manufacturer - Dolphin Fiberglass. I don't think I have way of knowing what exactly they paid for the acrylic but Jack Broyl looks to me an honest and nice gentleman.) That is entirely too much money. Polycast GP and Reynolds R cast are considered the best in the industry and they cost nothing close to that. To give an example, I bought (9) 4 x 8ft sheets of 2.250" thick Polycast GP for about $1800 per sheet 6 months ago from Piedmont Plastics. I bought two 6x10ft sheets of 1.25" thick material for about 3K in 2006. Acrylic pricing fluctuates wildly between vendors. Port Plastics is OK, Piedmont Plastics is good (not LV branch, poor customer service). Colorado branch is good. Reynolds Polymer is expensive but decent IMO. I consider Reynolds to be somewhat like Apple. Good stuff but unique. I believe the weight of each panel/sheet is on the Spartech website, I think each 4x8ft panel/sheet of the 2.250 stuff is around 500lbs. Finding glass this thick would be difficult, I would never use glass for this application and would not recommend glass for large tanks. Glass is good for smaller tanks. It weighs too much and is not as safe as acrylic. Many other reasons not to use glass, those are just two.
In terms of leakage. There is no acceptable allowance for leakage for aquariums if constructed by a professional. Here is how I see it, I would never degrade the quality of any of my tanks by cutting costs thru the use of an inferior grade or thinner acrylic. Im a craftsman similar to a fine hardwood furniture maker and my reputation is much more important to me than making a buck and producing a tank that bows like the bags fish come in or crazes in a few years. Some folks are ok with that as long as the tank is huge. I dont build that way. Quality must always be #1 above all else. Most acrylic tanks I see mass produced and many custom tanks made today are similar to a Yugo IMHO. Each of my tanks are heavy, very heavy all sides the same thickness and are built like Abrams Tank with the quality of a Rolls Royce, one at a time. They do cost more but there is nothing better. Back to leaks...leaks will never get better they will only get worse. No leakage should ever be allowed in any size tank if dealing with a professional.
Hope this helps Viktor, publish it if you think it will help others and feel free to ask more questions, I'll try my best to answer. It's how we advance our hobby.
