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FAQs about Canopies, Tops and Housings for Lighting for Marine Systems: Coating/Sealing...

Related Articles: Canopies, Covers & Lighting Fixtures, Marine Light, & Lighting, Moving Light Systems, Marine System Components, Used Gear

Related FAQs: Canopies 1, Canopies 2, & FAQs on Canopy/Cover: Rationale, Design/Engineering, Construction, Reflectors, Fans, Wiring, Repairing, & Marine System LightingFAQs 2, FAQs 3, Actinic Lighting, Metal Halide Lighting, Fluorescent Lighting, Compact Fluorescent Lighting Small System Lighting,

Paint for Inside of Canopy 8/1/05 What type of paint might you suggest for painting the inside of a canopy white, and perhaps the same for inside the stand to help reduce moisture being imparted to each?  How about a white, one part epoxy paint (saw this at Home Depot, by Behr). <Should do>   Wouldn't the epoxy style paint provide a nice hard, durable finish? <Yes> I also ran across another idea by someone else (on ReefCentral or some such) - a Behr white paint coated by a Minwax polycrylic clear gloss?  Any general ideas?  Thanks. <Epoxies, water based latexes and polyurethanes are my faves. Bob Fenner>

Marine Epoxy Paint Question -- 11/01/10
I would like to seal the wood inside of my canopy against water damage. Can you recommend a good sealant or paint that would be non-toxic?
<<You can go with a true epoxy paint if you want, but the trouble and expense is not necessary here. Like any paint job, the prep is key -- but a 100% Acrylic-Latex paint will do the job nicely. This is often sold as "Exterior Enamel" paint and you should be able to find it at most any hardware or home store>>
Any brand names?
<<BEHR, Glidden, etc. - any of the big names will do>>
<<Happy to share'¦ EricR>>

Canopy weight: Construction of Steel Canopy Frame 6/23/2010
Hello everyone!
<Hi Jason.>
I trust everyone is well. Things are pretty good with me.
<Fine, thanks.>
I have had my 250 gallon up and running for a few months now, and other than the devastating
velvet fiasco, things are ok. I wanted to ask a question. I have a steel stand (60x36x31) supporting my tank, and it is dead level, and strong (overbuilt). I feel very good about the structural integrity of the stand/tank. I was planning on making a canopy like I made the stand.
Steel frame, wood cabinet doors held on by magnets.
I would use much lighter steel ( I was considering thinner 1x1 square tubing) in the shape of a rectangle which would rest evenly all around the edges of the tank, (except where my plumbing comes over the edge of the tank). It would be 60x36x12. I have attached a jpeg to show you what I mean.
<Nice drawing. AutoCAD?>
Can you see any flaws with this plan?
Will this be too heavy for the tank?
<In my opinion, yes. 1 x 1 square tubing with a 0.250" wall thickness and rounded corners has a rough weight of 2 pounds per linear foot (Sharp corner is 2.55 lbs\ft). Looking at your drawing, that figures to roughly 88 pounds just for the frame, With the addition of wood, panels, this will easily top 100 lbs. Now if there is a way to have the stand support the canopy.>
I will have this powder coated also.
<Another consideration is that much metal in close proximity to the top of the tank, where all of your evaporation will occur, a high humidity, high salt, higher temperature (Lights) environment, could leave you with cracking, and corrosion anywhere there is a defect in the powder coating.
Which is why you can find several metal stands, but no metal canopies.
Also, many of the marine grade coatings can be toxic to marine life. >
Any input you can offer would be appreciated.
<Your design is sound, but I think you really need a different material other than steel.>


To Paint Or Not To Paint The Inside Of My Enclosed Canopy -- 07/16/09
I have read through your FAQ's and completely understand that you recommend Polyurethanes for inside a canopy.
<<If applying a 'clear' finish, yes. Thought in 'my' opinion, I think painting the interior a 'reflective color' is better>>
I am getting ready to install 2 of the TEKII T5 HO Retrofit kit 48 inch 2 x 54w which come with the TEKII reflectors. I will also be installing some LED's. I have an enclosed canopy and will be mounting these to the top of the canopy. The canopy is stained and sealed already. Would there be any value-add to painting the inside of the canopy white or some other reflective color?
<<As stated, in my opinion I feel there is. Even with the reflectors, light will 'escape' and be bounced around under the canopy. A reflective paint will help to bounce that light back down in to the tank. Now is this a 'big' difference/benefit over the stained and poly'd interior? I can't really say'¦but especially with Fluorescent bulbs, I think one needs all the help they can get>>
If so what kind of paint should I use?
<<I would use a gloss Latex Enamel. Do be sure to sand/roughen that Polyurethane surface to assure good adhesion>>
Would there be any heat issues with mounting these to the oak canopy?
<<Heat is most always an issue in a confined space such as this. I suggest providing some means of ventilation (small fan), and depending on the lighting fixture and how hot it gets you may even need to place a heat-shield (e.g. -- a piece of sheet aluminum) between the fixture and canopy top where the two make physical contact>>
Should I use the glass tops I have for the top of my tank or leave those off seeing as I have an enclosed canopy?
<<I prefer to NOT use any type of 'top' on a tank for reasons of improved gas exchange and ventilation/evaporative cooling>>
Thank you in advance for any and all info/advice!
<<Happy to share'¦ EricR>>

Stand, finishing... reading  1/2/09 Hello. I just finish building my fish tank stand. I want to stain it. What type of stain and coat would you recommend for the stand and also inside the canopy. Or is it just be easy to paint it? Then what type of paint. Thanks a lot. <Read here: http://wetwebmedia.com/aqstdfinishes.htm Bob Fenner>

Re: Stand, now canopy finishing  1/2/09 Thanks for info. Also i used wood glue for canopy. Is that ok? <... Yes... I would pilot drill, screw the pieces together additionally (likely you have done this), and coat, seal all per the last citation. BobF>

Re: Stand, coating  1/11/09 So I've decided to use Minwax stain and then Minwax spar urethane on the top of stain and inside canopy. Is that sounds ok? Do I use water based or oil based products? Thanks <Both are fine lines... but I like the oil-based myself... if you have a garage, somewhere you can apply, let the fumes, smell dissipate during drying/curing. Bob Fenner> Re: Stand Thanks, Bob <Welcome Phil>

Re: Stand  1/18/09 Hello, Bob. A quick question. I'm using oil based stain on my stand. Do I need to sand between coats of stain, and then also between coat of varnish? Thanks <Likely best to let dry/cure, then sand lightly, then varnish. B>

Painting 36x18 Hood Base plate  8/24/08 Hi I have been searching for a Black 36x18 Hood Base plate, and the only place that I have found it was at Thatpetplace.com, but unfortunately they are discontinued, but they do have it in the Oak. My husband is an Automotive Painter, so what we planned to do is just order the Oak and he will take it to work and paint it black. My question is would this be safe to have on the aquarium, or do I have to use a certain type of paint to do this with. Thank you in advance for your help in this situation. Tonya <There are better paints than others. Please read here: http://wetwebmedia.com/canopycoatg.htm Bob Fenner>

Re: Painting 36x18 Hood Baseplate -08/25/08 Well it turns out that I was able to order it through petscentral on Ebay. Don't know if you can include their name <We can... our mommies aren't here...> in this but if you can let the readers of your site know that they are great, have great customer service and go out of their way to get you what you are looking for. <Ah, thank you for this testimonial> You have a great site and I enjoy reading the FAQ's even if they don't pertain to my situation. Thanks again for all the help that you and your site has provided. Tonya

<Welcome! BobF>

Re: Painting 36x18 Hood Baseplate -08/25/08 Ok so would it be safe to use this type of paint? <"Car paint?" Likely so... once it's cured, it should be chemically inert... Am wondering how this will work, given that the paints used are likely formulated to "stick" to metal, plastics... B> Paint inside canopy  9/5/05 Hi crew. I was told to paint the inside of my canopy with exterior white high gloss acrylic latex, then finish off with two coats of polyurethane. After applying the paint I looked over the FAQ's. The paint says it provides mildew resistant coating. From what I read this is bad. Do I sand down all the paint and restart, apply a different paint over the existing paint, or will the poly seal it to be safe. Thank You, Terry <The two coats of Polyurethane will seal the mildewcide from contact... Am a big fan of urethanes... Bob Fenner> Wood finishing, plumber's tape for threaded connections, painted backgrounds, whew! Hi Guys (a generic term that includes the female members of the crew ;o) <Watch this...> I have searched WWM & couldn't find a relevant answer - hopefully I've not missed! <We'll see... or add to it> Just a quickie re finishing the woodwork for my new 24" cube - I will need some sort of finish on the veneered panels that I have now got for the new tanks cabinet and open topped hood but I am not sure what would be most suitable, I have been looking for some sort of polyurethane varnish type stuff but have so far drawn a blank (maybe its just called something else in the UK?).  The main area for concern will clearly be the hood woodwork as this will be the closest to the (salt) water & thus more chance of particles of finish (or some sort of reaction leading to leaching of nasties) entering the water column (clearly something to be avoided if at all possible (however I believe in planning for the worst - comes from working for the UK government I guess lol!!)) Any pointers to a suitable finish would be more than welcome. <Polyurethanes are fine (durable, non-toxic once cured, attractive), though I am a bigger fan of Varathanes (as you speculate, perhaps a "Yank" (formerly colony) term... These come in different reflectivities (I like the less shiny), and are even more durable> Would you be able to confirm my suspicion that PTFE (plumbers) tape will be fine for sealing my new closed loop system? From what I can gather this should be fine and nicely inert. <Is... though I am a bigger fan (here we go again) of using 100% Silicone (the same material/el used for making glass aquariums... for thread to thread connections... makes a nice flexible joining, and allows for easy unthreading if needed later on... and "makes a seal" rather than allowing salt creep over time. Bob Fenner> Ok just 1 other question ;o) <Oh!> I also need to paint the back (outside obviously) of the tank black to match the weir - I am planning to use enamel paint - Japblack I think the brand is (do you see any problems here?) <Am unfamiliar with this term> - will I be OK just to go ahead and paint this or would I be better running some sandpaper or such over the area to be painted to provide a "key" or rougher surface for the paint to adhere to? <Mmm, I have used latex or water-based in-door wall paint here... sans scratching... to good effect...> Sincere thanks as usual in anticipation Cheers   Chris

Aquarium-safe wood sealant  11/16/06 Hi crew, <David> I'm planning to build a wood canopy for one of my tanks.  I'm thinking of using 1/8" veneered ply for the facing, to keep the cost down, but I'm concerned about chemicals from the wood (formaldehyde) ending up in the water via condensation or off gassing. <And rotting by way of moisture, heat...> What do you recommend using as a sealant, both to protect the wood from moisture damage and to prevent contamination of the water?  I've Googled for "safe wood sealant" and came up with some products that claim to reduce off gassing-- do any of you folks have any experience with these? Thanks, -Dave <Urethanes, polyurethanes, Varathanes are my faves... come in various colors, reflectivities... readily available from "hardware" stores. Bob Fenner>

Re: Aquarium-safe wood sealant  11/16/06 Bob, you don't see any problems with off gassing/leaching from polyurethanes? Don't want to end up with any 3-toed fish! <Heeee! No worries... once cured (about a day) there are no such issues. BobF>

Polyurethane   1/12/06 Hi Bob, <David> In a recent exchange, you suggested using polyurethane as a sealant for wood canopies.  I've also seen other references to this on WWM. <Yes> Well, I just built a small canopy for a 3g aquarium, using 4"x1/4" birch molding for the sides and 1/8" MDF <Mmm, I really don't like this material around water... like me, it starts to swell... http://home.att.net/~waterfront-woods/Articles/Plywood.htm> veneered ply for the top.  I did 3 coats of poly, taking special care to seal the edges well.  Let the poly cure for 3 weeks.  Left some openings for airflow, but there's quite a bit of condensation on the inside of the canopy when the lights are off.  After 2 days, the top has already started to warp! <Yes, very common> In retrospect, I think the 1/8" MDF was a particularly bad idea, but Id've thought the poly would seal pretty well against moisture. <Mmm, no...>   So I asked a couple of people about this.  At the LSWS (local specialty wood shop) they told me that polyurethane is not appropriate for high-moisture environments, and that plywood of any thickness will eventually warp unless it's marine-grade ply (which is made from mahogany or teak, and probably some special type of glue). <What did they suggest?> And a friend of mine who has extensive experience with wood in marine environments told me that the common oil-modified poly you get in hardware stores won't do it... water-based poly is worse...  The only kind of poly that will completely seal against moisture is two-part poly, which is usually sold in marine supply shops.  He says you can coat balsa wood in 2-part poly and completely submerge it in salt water with no worry. Anyway, thought I'd post some feedback/experience, maybe a note of caution for other WWM'ers. Best, -Dave <I thank you for this input. Will place/share. Bob Fenner, who has used many gallons of urethanes... and was likely lucky> Re: Polyurethane   1/12/06 Bob, <David> At the wood shop, they suggested the marine-grade plywood.  Of course, they may have wanted to sell me some pricey marine-grade plywood. <Is expensive... but marine grade... is great... I/we made whole facilities, exhibits out of this (coated) along with glass viewing panels and Silastic years back... along with fiberglass strip cloth and hot/coating resin...> My friend (who lived on a few tons of floating teak for 14 years) said that even marine-grade ply will take on some moisture and swell over time, although not as much.   <Agreed> His suggestion was use any old plywood, and coat it with a marine-grade polyurethane.  Specifically, he suggested two-part poly (see http://www.epoxyproducts.com/lpu.html). <Yes... I do think this is best/better> I've seen some one-part polys marketed as "marine-grade" but I'm suspicious... when you think about it, a one-part poly has to be somewhat porous because it requires cures with air and water.  Two-part polys don't have this requirement because they don't need air/water to cure. I suspect this is mostly an issue with plywood and/or soft, open-grained woods... I steamed and bent a piece of birch for the front piece of my canopy, so it'll be interesting to see what happens there... Best, -Dave <Thank you for this follow-up, your thoughts. Bob Fenner> Painting custom canopy <<Hi Jason and Karalyn>> I've searched your site and read up on canopy painting recommendations. Based on this information I'm planning on painting inside and out with a black latex based paint (to match the stand) and then coating with a Varathane product. Will this finish be safe over a reef setup? <<Yes, should be fine.>> Also, the retro kit reflector will cover the inside top, but not the sides. Will this make a difference or should I go with white paint inside, or look for more reflector? Thanks for any input. <<Either way will work. White latex or reflector will help reflect more light. Some of the manufacturers make a deep reflector which might extend down the sides more (PFO).>>  Jason & Karalyn Jacobs <<Cheers! Craig>>

Paint for canopy Hello, I hope you can help me, I am so confused about the type of paint to use on my "canopy" (it is more a light shield for my suspended MH fixture: a rectangular box with no top).  I fear that I have made a real mistake in painting it with acrylic/latex paint.  I was then going to put a clear polyurethane over that.  In your opinion, should I build another and just use a polyurethane stain.  (I wanted the canopy black on the outside).  For the sake of my reef tank inhabitants, I hope you can give me a definitive answer, as I don't want to make a mistake.  BTW, I used BC plywood.   Thanks C Pawley <Please see here: http://www.wetwebmedia.com/marine/setup/lighting/canopyfaqs.htm and here: http://www.wetwebmedia.com/tkstdfaq.htm and the next FAQs file beyond re. Bob Fenner>

Paint for Canopy Hello, Hope you are well today! <Yes, thank you> I was hoping you could answer a question for me: I have built a light shield for my suspended MH fixture.  (basically, a canopy without a cover)  I am going to paint it and would like your recommendations as far as sealants, primers and paints that would be non-toxic.  I used BC pine plywood and, this may be a dumb question, but, here goes:  I should prime it, paint it, then seal it, right?? <This is one approach to protecting the wood. You might also consider coating the exterior with polyurethane.> Thanks for your time and in advance for your response. Cheri Pawlak <You're welcome. Bob Fenner>

Canopy Paint - 9/24/03 Can you suggest a paint for the inside of a light hood over an open reef tank?   <tub&tile or swimming pool 2-part epoxies work very well and dry hard/non-toxic. Else, any baby safe latex paint that you coat with polyurethane will be fine if above water> I have some bathroom paint lying around and was hoping to use it. The problem is it contains a mildewcide. <alas no... it is very toxic to aquatic life because of the anti-fouling agents as you have suspected> I was hoping to use it if  I sealed it with a few clear coats of polyurethane. <not worth the risk> Is this even all that critical, since most of the surface area of the hood will be covered with reflectors for the new T-5 lights? <agreed... but still not worth the risk.> Get that next book going, I am out of good reading material. <writing it as we speak <G>.> Thanks as always, Ken <thank you, my friend... Anthony>

Lighting Canopy Questions... Hello, <Hi there! Scott F. with you today!> I have a 90 gallon tank with a base and a canopy top. I want to buy PC lights 4 X 96 watts for my tank. Is this too much or too light for fish, live rock, mushrooms, invert, and maybe soft corals, anemones??? <Nope! Sounds just right to me!> Also I went to my local glass shop the other day to see if they could make my a cover for my lights I want to get. SO basically The cover I discussed with them is going to be made out of Lexan. The light will be placed in this cover, basically it is a rectangular box with an acrylic hinge top. SO the light will be mounted in this Lexan box and the Lexan cover/box will be mounted on the canopy it self. Is this a bad idea?? <Only if it prevents heat from escaping, and filters out too much of the light...> I did not want a glass canopy in the inside of my wooden canopy top. So the water and light will have the Lexan cover between them. Every time I open the top of the canopy I will see the light fixture in a Lexan box that is mounted on the canopy cover. I talked to them about putting some fans into the design and say they could do it. Should I have two fans on one side exhausting heat?? Or should I make the Lexan cover longer and put two fans on one side sucking air in and two fans on the other side exhausting air???? <That would be cool (no pun intended), if you could have two fans blowing in, and two blowing out...> By the way the tank is 48 X 18 X 24 inches. The light fixture will be 36 inches long. Please tell me what you think. Will the Lexan cover discolor, melt from the four pc lights that will be only about 1-2 away from it. <Not sure...I'd consult the glass place...Tell them about your intentions, and verify if this material can stand up to the potential heat...> The reason for the mounted on cover on the canopies top itself is that there is a little trap door in the front of the canopy's heavy (mahogany canopy and base, solid mahogany)) for feeding the fish. If I put a glass canopy on the top of the tank  I would have to open the canopy's top or trap door and still have to open the glass canopy to feed the fish/. <Clever!> Please reply as soon as possible. Zeyad Yusuf <Well, Zeyad, I think that your idea is fine...just make sure that the hood ventilates properly...>   P.S  Thank you and I love your site!!! <And we love to be here for our fellow hobbyists! Good luck! Regards, Scott F>

Lighting hood coating I recently made a new hood for my 75 gal tank. It has bare wood in places that may come in contact with salt water. What would be best to protect (paint) the exposed wood with? It is not just a flat surface that I can put a laminate on. Where would I find such a product. <Either an epoxy based paint or my fave, a polyurethane> Also my lighting will be a 660 IceCap (3-lamps) and a 100w MH. Should I use VHO actinic (1 or 2) and can I use GE ultra daylight lamps in place of a 50/50? What will be my best set-up for the above lighting scheme? Thanks, Spence <Depends on what you're keeping, what you want it to do. Please read here:  http://www.wetwebmedia.com/marine/setup/index.htm  skip down to the area: Lights/Lighting... and read on. Bob Fenner>
Re: lighting hood coating
Thanks Bob, <Welcome> My next question is a regular polyurethane that you use to finish a kitchen table? Glossy or flat, and how many coats would I use so that it would last for years and hold up to the inevitable salt creep. Thanks again, Spence <Is the same stuff as for tables (I REALLY like this material)... the finish is up to you... comes in a rainbow of reflectivities... Check them out at Lowe's, HD... and at least two coats... maybe with a light steel-wooling tween... and don't forget some inexpensive "throw away" brushes! Bob Fenner>
Re: lighting hood coating
Bob, Thanks again I was really in a conundrum(sp?) about what wouldn't be toxic to my fish and inverts. urethane it is!  Spence <Good enough for bowling alley lanes and my countertops! Beautiful, enduring, and fun to apply! Bob F>

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