"Pros and cons" experienced comments please

  • We are currently upgrading MFK. thanks! -neo
I have had bad experiences when top coating polyester with epoxies ( been in the fiberglass business professionally for nearly 26 years and have first hand experience mixing the types of resigns ) , I know all the literature says that epoxy sticks to polyester just fine..... only on well cured poly-ester.... and professionally I never mix the two If it made with polyester repair are either poly or vinyl ester.... anything below the waterline should be vinyl-ester and with that stuff it needs to be primed with vinyl-ester primer. I know epoxies are far more expensive but in the long run epoxies flex and stretch better the Esters do , I just believe that if price is not an issue total layup and top coat use some form of NON Blushing epoxy (which you can pigmented to the color of your choosing )Longevity and performance were key at the beginning of the thread and cost didn't matter....wants the best

So after glassing what products? Keep in mind I'm installing a viewing widow so product needs to be able to allow silicone to bond.... So window can seal


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Just look into sweetwater epoxy sold on aquaticeco.com. I have had no fails with this brand-no leaks! 300 gallons is not 500 but I can tell you, I've made several tanks. Product should last 20 years with care. No recoating after a few years, no chipping, and no cracking. Used with fiberglass and your tank will be solid. I also mentioned its ability to bond with silicone very well.

Ok I will look into this"
Thank you


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Just look into sweetwater epoxy sold on aquaticeco.com. I have had no fails with this brand-no leaks! 300 gallons is not 500 but I can tell you, I've made several tanks. Product should last 20 years with care. No recoating after a few years, no chipping, and no cracking. Used with fiberglass and your tank will be solid. I also mentioned its ability to bond with silicone very well.

Thanks ^^


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Methods of waterproofing a plywood tank.

1. Two part epoxy paint
The most commonly used and reliable epoxy paint for plywood aquarium builds is Sweetwater epoxy available from Aquatic Ecosystems : http://www.aquaticeco.com/subcategor...aints-1-Gallon
It is completely non toxic when cured and has good adhesion to plywood. This epoxy paint has solvents mixed in and is only 65-72% solids. The solvents mean that it ships as a hazmat product and will let out strong, toxic fumes while curing so a well-ventilated workspace is essential when using this product. It also means that it has a nice consistency and is very easy to work with and apply. Sweetwater can be used as a stand-alone product for waterproofing a plywood aquarium. While several members have done this successfully, others have reported that leaks have developed after long periods of use due to stress fractures forming at seams or pinholes due to falling decor. It is therefore important to have a well built structure when using this product as excessive flex could potentially contribute to leaks. Silicone will adhere well to Sweetwater so when sealing a tank with this method you should first apply the Sweetwater and then silicone in your viewing panels.

Epoxy paint summary

Pros: Easy to apply, available in a range of colors, silicone will stick to it making window installation easy.

Cons: Toxic solvent requires hazmat shipping and well ventilated workspace, does not add structural strength to a build, potential risk of failure in an inadequately supported tank with excessive flex.

2. Fiberglass resin with epoxy paint top coat
Reinforcing a plywood coating with fiberglass is an excellent way to add structural strength to the build and impact resistance to your coating. The cheapest way to apply fiberglass to a build is to use fiberglass resin to wet out the cloth. Lightweight fiberglass cloth and fiberglass resin are available from online vendors and are also generally easily found in “big box” stores like Home Depot and Lowes in the US eg. http://www.lowes.com/pd_73902-63-E77...tId=3143485&Ns =p_np_epoch_date|0&pl=1&currentURL=/pl_Elmer%27s_4294934474%204294961757_40_
Fiberglass resin is generally polyester resin and requires a small amount of hardener to be added as a catalyst. Effective application of fiberglass takes a little skill but is fairly easy to learn with a little practice. It is important to avoid bubbles in the fiberglass layer which may ultimately pop under water pressures and compromise your seal. Polyester fiberglass resin is fairly cheap but has a very strong smell and requires a well ventilated workspace. In addition, it is not sufficient as a standalone waterproof barrier coating and will leach out chemicals into your aquarium water. Therefore, you must finish a fiberglass resin coated aquarium with a non toxic, waterproof topcoat. Sweetwater (see previous section) is an excellent product for this purpose. Using Sweetwater over a layer of fiberglass overcomes most of the potential cons of Sweewater alone.

Fiberglass resin + epoxy paint summary

Pros: Relatively cheap way to add structural strength and impact resistance to your build, epoxy topcoat is available in a range of colors, silicone will stick to it making window installation easy.

Cons: Fiberglass application requires some practice and skill, toxic fumes in the resin and paint require well ventilated workspace, fiberglass resin is not sufficient as a stand-alone barrier coating.

3. Two-part marine epoxy resin
There are many different brands of epoxy resin available but only true two-part marine epoxies should be used for plywood aquarium builds. These epoxies have a long established and successful history in waterproofing wooden boats. They differ from epoxy paints in that they are 100% solids. Several brands are available but some tried and true options include:
West Systems 105 (one of the more expensive): http://www.westsystem.com/ss/epoxy-resins-and-hardeners
US Composites (cheaper option): http://www.shopmaninc.com/epoxy.html
Max ACR (newer, relatively affordable epoxy being marketed specifically for aquariums): [Ebay Link Removed] (search for the seller “polymerproducts” on ebay)
There are many other marine epoxy brands out there that you could use but these three cover the spectrum of price and have all been successfully used in waterproofing plywood aquariums. Marine epoxies come as a resin and a separate hardener that have to be mixed in a precise ratio. It is best to use slow hardeners when sealing a tank with these products to give you a longer working time and better penetration into the wood. The West Systems use guide is an excellent resource to learn how to properly use marine epoxy: http://westsystem.com/ss/use-guides/
I strongly recommend reading every section of the guide before beginning to work with these products.
Marine epoxies can be used as a standalone product to provide a completely waterproof and non-toxic coating for a plywood tank. However, they are fairly brittle when cured and can be susceptible to stress fractures at seams and damage from impact which will compromise the barrier coating. Please see http://www.jonolavsakvarium.com/eng_...t/article.html
The best way to avoid these issues is to incorporate a layer of fiberglass cloth into the epoxy resin. Epoxy resins can be used to wet out fiberglass cloth in much the same way as polyester fiberglass resin but offer several advantages. There is not strong smell, the cured resin layer is completely waterproof and non toxic and is slightly less brittle than polyester resin. With the exception of cost, epoxy resin is an all around better option than polyester fiberglass resin. As discussed above, wetting out fiberglass cloth does take a little practice but with a little skill is an excellent way to add significant structural strength to your aquarium.
When used with thickening agents such as colloidal silica, marine epoxy can also function as an excellent adhesive, particularly for slightly loose joints or joints where you cannot deliver high clamping pressure. It can therefore also be useful as a waterproof adhesive during the construction and assembly of a plywood aquarium.
Silicone will adhere well to epoxy resin so waterproof your tank first and then silicone in your glass viewing windows. Epoxy resins can be tinted if you want a colored coating but will usually still show some wood grain. Sweetwater epoxy can be used as a topcoat if solid color is desired.

Two part marine epoxy summary

Pros: Can add significant structural strength to a build, particularly when used with fiberglass. Minimal smell. Effective standalone waterproof barrier layer. Silicone will stick to it making window installation easy.

Cons: Expensive, can suffer from stress fractures if used without fiberglass on an inadequately supported structure.

4. Pond Shield
Pond Shield is a 100% solids two part epoxy resin available from Pond Armor http://www.pondarmor.com/ It is different enough from the marine epoxies described above that I thought I should give it its own section. Pond shield is non toxic (so no Hazmat shipping is required). It has practically no odor and is safe to apply indoors. Pond shield is an extremely thick epoxy which can make it somewhat challenging to work with. The black pond shield is the thickest and has a consistency slightly thinner than honey. It can be thinned slightly with denatured alcohol to make it more workable, but thinning also increases the risk of not getting the required thickness in a single coat. One 1.5qt kit of Pond Shield claims to cover 60sq ft at 10mil thickness. For many applications a single coat is sufficient to get a 10mil coat that is completely waterproof.
Pond Shield is best suited to waterproofing well-supported structures with no flex. If you have any concerns about the integrity of your seams it is best to fiberglass them to prevent the formation of potential stress fractures. Pond Shield is ideal for sealing concrete tanks. While it adheres to wood it adheres even better to concrete so one option when using it on a plywood tank is to first line the inside of the tank with Hardiboard. If you instead choose to apply it directly to a wood aquarium it is best to first do a light wash with 30-40% alcohol-thinned Pond Shield to get better penetration into the wood and follow this with a single coat of unthinned, or very slightly thinned Pond Shield.
In my personal experience I have found that the thick consistency of Pond Shield can make it challenging to work with and results in several areas that require touching up after the initial coat. Careful inspection and touch up is critical to the success of using this product.

Pond Shield summary

Pros: Completely non-toxic and odor free. Available in a range of colors. Requires only a single coat and touch up. Silicone will stick to it making window installation easy.

Cons: Thick consistency can make it difficult to work with. While it remains somewhat flexible after curing it is susceptible to stress fractures in poorly supported structures.

5. Liquid rubber
These waterproofing products are elastomeric emulsions that remain highly flexible after curing. While there are a number of these products available, some examples of those that have been successfully used with plywood aquariums are
Zavlar / Permadri Pond Coat (in the US) http://www.permadri.com/pond-coat.html
and Ames Blue Max http://www.amesresearch.com/bluemax.htm .
These products have minimal odor and are easy to apply. Zavlar/Pond Coat requires several coat to achieve a 40mil thickness that provides a waterproof barrier. One gallon will cover 30sq ft at 40mil thickness. The primary advantage of these products is that their incredible flexibility, which allows them stretch and resist fractures in inadequately supported structures. However, it is still a good idea to use drywall tape on seams while applying these products in order to to reduce potential stress on the coating at these spots.
Zavlar/Pond Coat will initially appear brown and will dry to a black coating. However this black coating will gradually turn back to brown after being submerged for a period of time. Ames Blue Max dries to a translucent blue color.
Zavlar/Pond Coat will not cure when applied over silicone. Similarly, silicone will not adhere to cured Pond Coat. This incompatibility with silicone is a disadvantage of these products but is easily overcome. One strategy is to use butyl rubber, polyurethane caulk or 3M 5200 instead of silicone. The viewing window should be installed first with one of these products and then the Zavlar/Pond Coat is used to waterproof the inside and paint over the cured caulk. As an additional measure of security I recommend using a small amount of epoxy to first waterproof the area where the viewing window will be installed, such that epoxy layer bridges the seam between the zavlar and caulk. This way, in the event the zavlar separates from the caulk the epoxy provides an additional waterproof layer that will prevent leakage.

Liquid rubber summary

Pros: Highly flexible coating resists fractures even in poorly supported tanks. Easy to apply. Minimal smell.

Cons: Limited choice of colors (brown in the case of Zavlar/Pond Coat, bright blue in the case of Ames). Incompatibility with silicone slightly complicates window installation.



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Ok, my 2 cents.
Look up other threads about fiber-glassing the outside of the tank. VerbleKint statements have validity. A lot of "glass" has a wetting agent in it that is toxic to fish. This is one reason we didnt glass the inside of my tank. The other reason is strength. My tank is interior is coated in MAC ACR which was done at their facility as a "lets do this and see what happens". It was their (and mine) first one and the results couldn't be better.

A "bite" coat was applied to the bare plywood. Its thinned down a bit to allow it to penetrate into the wood. Halfway thru the cure a second regular coat was applied. A day or so later we sanded this coat and applied a third and last coat. There's no inside fiberglass...its on the outside of the tank. The tank was filled with water and hung off the edge of a pallet on a forklift for at least 24 hrs. Nothing. The bowing was only about 1/8 of an inch and the tank is 206 gallons. That was several years ago.

Somewhere here there are a couple of threads on glassing the outside of the tank. The engineer at Polymer Composites (MAX ACR) really drilled it into me this is the way to go. I think someone here threaded the same response they got from Sweetwater or some other epoxy manufacturer.

Also, separate from my aquarium stuff, I work with gel coated fiberglass that is underwater all the time. It absorbs water. As it "dries out" it warps some.

Something to consider. Like I said, just my 2 cents.
 
If you look at every large build, you will find issues with every type of coating except for Max ACR. Those issues range from toxicity, workability, leaks, pin holes, smell, etc. I have not seen a single thread on MFK that has a complaint about Max ACR. If I had a chance to do my tank completely over, other than minor size changes, and design of the floor, I would only change the coating to be Max ACR and use fiberglass mat on the seams.
 
Ok but would I still need to use a top coat? Or no? Seems like the max acr stuff is pretty good.... Can it crack???or flex???? Can it handle pressure like a good thick fiberglass???? Can I fiberglass the complete interior if my tank lil a bath tub and then apply this MAX ACR over the top of that? Will it bond....can I bond my silicon for the window to Max ACR?

I know fiberglass alone is not aquarium safe true water proofing agents should keep the toxins under that layer unless not properly sealed.... So will MAX ACR seal in the toxins if I did glass the entire inside of the tank and apply the MAX ACR as a top coat?

If i still need to apply a top coat or just want to be safe will these bond to Max ACR? And IYO which of these products are best>>>

Sweet water? Or Permadri?

I really appreciate all of these replys.... Felt a little stuck and alone for a bit lol
 
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