Cal Posted January 3, 2003 Share Posted January 3, 2003 Let me start off by saying this is my first post ever so hello to all. Greetings out of the way let me get down to the issue I have. I am DIYing a canopy for a 10 gallon. I have everything under control I believe except the reflector. I did a search and read all the posts about reflectors. I didn't find exactly what I was looking for but got many ideas. With that I am making multiple canopies since this is the first time I have ever done anything with these issues. Normal woodworking not withstanding. Here is the issue I have. I am afraid of excess heat and chance of fire. I am going to be putting a 175watt MH and two 36watt actinic PC bulbs in this canopy. I am making different height canopies for testing and different fan combinations. If I go without a homemade reflector and just paint the inside of the canopy flat white will there by a fire hazard issue? I will be trying to cool this canopy so it doesn't cook the tank with four 80mm 19.5CFM papst fans with voltage control for rpm/sound reasons. Next question but related. If I go with an aluminium reflector painted flatwhite behind the bulbs to try and prevent wood from catching fire should I screw it straight to the wood or use standoffs to let some air flow behind the reflector? Okay well this turned into a much bigger post then I had hoped and for that I am sorry. I hope anyone who has dealt with this issue will have the patience to read this entire thing and give me some pointers. Link to comment
BCOrchidGuy Posted January 5, 2003 Share Posted January 5, 2003 The aluminum reflectors can be very very efficient, flat white paint may not be very efficient. Definately put a spacer between the back of the reflector and the wood for airflow. Try to keep your MH light 8 inches to a foot away from the glass cover over the tank. Good luck with it and keep us posted Link to comment
ross76053 Posted January 5, 2003 Share Posted January 5, 2003 I agree with the spacers - and I'm glad to see you'll be using fans. Don't use white paint alone - you've got to use a good sealant, like Varathane, four coats minimum. Link to comment
Cal Posted January 5, 2003 Author Share Posted January 5, 2003 Hello again, Glad I got some replies today since I have four canopies made ready for testing. All that needs to be done is paint ,seal, install reflectors and sockets/tubes. As for flat white paint I read after a search that it reflects the most light. So that is what I bought. I also read your canopy plans ross and your suggestion about varathane and picked it up. Since these are just test subjects I dont plan on using them for real I dont plan on doing the outside since that is pure for aesthetics. Here are the canopy specs, to follow test conditions. The four canopies I made are all the same size but the differences are. Canopy #1 has 2 fans blowing in and 2 blowing out for a total of 39CFM, 24dBA at full voltage. It also has an aluminum reflector painted flat white which will have 1/4" standoffs supporting it. Canopy #2 has 1 fan blowing in and 1 blowing out got a total of 19.5CFM, 15dBA at full voltage. It also has an aluminum reflector painted flat white which will have 1/4" standoffs supporting it. Canopy #3 has 2 fans blowing in and 2 blowing out for a total of 39CFM, 24dBA at full voltage. But it does not have a reflector it will just be painted flat white inside and then sealed. Canopy #4 has 1 fan blowing in and 1 blowing out got a total of 19.5CFM, 15dBA at full voltage. But it does not have a reflector it will just be painted flat white inside and then sealed. To test I am going to measure temp behind reflector, temp in between bulbs and glass, temp on tank side of glass , temp at very bottom of tank and the temp at the very top of canopy. I might also rent a lux meter from the local photography place and see the difference between relfector and not in terms of light at the source I want it. For giggles I will also use my SPL meter to measure the sound of fans at various voltages even though my own ears will tell me what is annoying and what is not. The lights will be on an hour before any real meaningful temp measures are written down. But I will check every 5 minutes just for insurance. If anyone has any suggestions or thinks I should do something different please let me know. Results will probably take me about a week so if you have anything to add or say between now and next Sunday please post away. Why I edited: I had a typo, sorry. Link to comment
glazer Posted January 5, 2003 Share Posted January 5, 2003 cal, Just a word of caution.... the white paint you bought for the reflectors, if it's "high-temp" paint made for appliances and such you should be fine. Anything else though will probably blister off and peel quite quickly from the heat of the bulb. Peeling paint falling on that hot bulb.... uh, you got a prob. Most white reflectors are either anodized or powder-coated and then baked for curing. And as far as what you are saying about reflective qualities.... I read a quite lengthy article published by NASA awhile back (can't find it now) and yes.... they did say that flat white was much better at distributing the light. Link to comment
Cal Posted January 5, 2003 Author Share Posted January 5, 2003 glazer, Yes, the paint for the aluminum is rust oleum high heat formula. It says it is resitant up to 1200 F. However I never thought about powder coating. I wish I had a spare oven that I could use to do it. Would be pretty easy to goto an automotive place and get a flat white powder coat. I don't think the wife would like it very much if I used her oven for this project. Link to comment
technoshaman Posted January 5, 2003 Share Posted January 5, 2003 Also what they commonly sell as 'Engine Block' paint in pep boys / trak auto is rated for high temperatures. I haven't used any on my tank furniture so watch out for heat related emissions possibly. It works like a champ for painting / modding up computer parts and cases in high temperature areas. Link to comment
BCOrchidGuy Posted January 6, 2003 Share Posted January 6, 2003 Even your rustoleum is rated at a bare minimum for MH, also my understanding of powder coating is that it is electonically put on the object and then baked at well over 1000 degrees for a period of time. Find an industrial painter and they should be able to do it, I just can't beleive that flat white is a better reflector than polished aluminum... oh well I'm here to learn Link to comment
Cal Posted January 6, 2003 Author Share Posted January 6, 2003 BCOrchidGuy, The aluminum gets no where near 1200 degrees fahrenheit. It peaked at 159.12 degrees F. As for powder coating they make home kits for automotive. You ground what you are going to coat and spray the electrostatically charged powder on the part then bake at 450 for 20-30 minutes depending on the piece. There is a few places around here that do powder coating and plating but since this paint is going to work I wont be looking into it. Link to comment
BCOrchidGuy Posted January 6, 2003 Share Posted January 6, 2003 It is amazing that the aluminum only got that hot seeing as MH bulbs burn at or around 1000 degrees, I guess temp falls off faster than light the further you get away from the source. Never heard of this do it yourself powder coating either, I used to paint semi's and other heavy equipnemt, we had to send out all our stuff for powder coating. I guess things change... Link to comment
Cal Posted January 7, 2003 Author Share Posted January 7, 2003 Update- Ran into a snag so it is back to the drawing board. I was running some water temp tests and found I can't deal with the noise or water temp rise. The only setup that that kept me relatively happy was the one with 2 intakes and 2 outakes for air circulation. Room was an ambient 78 and I set the water to 78 before lights and it rose to over 80 degrees after 6 hours. There are few solutions I can think of to correct this. Use a chiller on the tank, but then I am still left with an annoying fan racket. Raise the hood height pulling light away more. Again still left with fan racket plus the canopy would be aesthetics of the tank look. Or find a better canopy cooling solution. All this testing has helped me nail down some design issues though. 1. aluminum painted reflector is in. 2. 30CFM in and out 3. nothing more than 20dBA/1m New Plan- No fans, dual fans and quadruple 80mm fans are out, dual 120mm fans in. I ordered two Papst 4412-PGL 120mm fans. One will be intake one will be outlet. At 12v they do roughly 1600rpm moving 55CFM at 26dBA. I plan to crank them down to 9v which should be around 1300rpm and 36CFM. We shall see if this will drop the dBA down enough to not annoy me. Sometime tomorrow I plan to pick up more poplar and construct the canopy. More tests to follow after that. OT: In the middle of writing this update my primary systems monitor failed so I had to switch systems and rewrite. Not been a good day today. Link to comment
Cami Posted January 10, 2003 Share Posted January 10, 2003 Hi, I'm new to the message board though I have been trying to post for over a month, and even though I have been a registered user the whole time, today is the first time it has allowed me to do so. I'm a nano newbe and will have many questions in other threads, but in this one I think I can help. Cal, always, when using two or more fans, have them all blowing into the hood. Drill holes where the hot air can flow out. Use the tendency of hot air to rise to help the circulation by placing the fans as low as possible and the holes as high as possible. Plan the air's path to flow over and around the items that need cooling. In your case you want as much air as possible to flow between the reflector and the wood above it. A good design with two fans is one at each end, (both blowing in,) and vents in the center top. Hot air leaving the hood is vented away from it and there is no secondary heating. If you set it up with one in and one out, the fan blowing out will fail quickly due to the extreme temps. With both blowing in they are self cooling and the fans will live a long time. Just my 2 cents, Cami in Sarasota Florida Link to comment
Cal Posted January 12, 2003 Author Share Posted January 12, 2003 Finally all finished with my canopies. I was only going to run one nano but now I am going to do two. I am doing it as an experiment in lighting. One canopy is 4" from water level and has 4 PC 36watt tubes in it with no fan cooling just an open back. The other has variable depth, 3" from water is the PC actinics and then 9" from water level is the MH. Next to the MH are the fans. Both solutions dont make any noticable temp rise in the tanks. I am now designing stands for the 10 gallons. After that it will finally be time to get the cycling and the real fun begins. Thank you everyone who gave suggestions and pointers. Maybe one day I will get enough spunk up to learn photography so you can see the work you helped to make. Again thank you everyone. Link to comment
BHRay Posted January 16, 2003 Share Posted January 16, 2003 Just an idea. I a previous life I worked on analytical equipment that went into inductrial smokestacks. Perhaps they didn't get as warm as these hoods do, but we used to use reflective materials that were made by 3M. I think the orginal use was for reflective safety applications. We used them because they just worked for us. We used to get it in a roll which produced a 3" wide strip of it with an adhesive back. I'm not sure what the adhesive temperature spec was, but it might work. Also, it may have come in larger sections. Newbie here, just an idea. Link to comment
SonicBlue02 Posted January 28, 2003 Share Posted January 28, 2003 Defintely do the bigger 120mm fans... I always use the bigger fans on my computers, more air, less noise. How did you hook the fans up for your canopies? I am curious how you are changing the voltage also. I am thinking of doing this exact same setup, 1 120mm in, 1 out, but not sure how I am going to provide power and voltage regulation. Thanks! Link to comment
Cami Posted January 29, 2003 Share Posted January 29, 2003 Two more cents. Whether you use 120mm fans or ones twice that size, they'll be more efficient with both blowing in and they will last much longer. You can do the math. With a pair of 45 cfm fans blowing one in and one out, you will move only 45 cfm of air through the canopy. With both 45 cfm fans blowing into the canopy and vents in the center upper rear you will move 90cfm of air through it. Twice the cooling and both fans will last much longer since the bearings will always be bathe in cool dry air. Try it both ways if you need to prove it to yourself, measuring the temp in the canopy both ways. Cami Link to comment
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