Polycarbonate aquarium tops?

[Reefinmike]

Hey all, i’m looking for tips and suggestions regarding using polycarbonate as aquarium tops. Long story short, I need to seal off my display from the high co2 air in my home. My skimmer will draw fresh air from outside through the display’s surface. With the three bulkheads I need to run through the tops and different areas of the tank i need to access, its just way to difficult to do with glass.

I’ve heard that polycarbonate is much more warp resistant than acrylic. My tank is a 90 marineland corner overflow tank. My kessil 360’s sit 4” above where the tops would be and 4 54w t5 bulbs are 3” above. The t5’s are on 2 at a time staggered with only a 1hr overlap. I have four 3” vent fans so the canopy is vented well. How well will this material hold up to my lighting and what thickness is needed to eliminate warping? I could use 3/8” if necessary but .220” is much more affordable. Does anyone have experience here? I need a 100% seal from inside air. If warping is inevitable i could drill and tap around the outer rim and secure the top to the tank trim with nylon screws. Lids could be reinforced with a couple ribs. I’ve never worked with this material so i’m not sure what to expect

Thanks for any and all input here

 

[HotRocks]

I cant answer this, but I can bump it for you.

Maybe try to post a link to this thread in the DIY section. There are many helpful members that frequent there!!!

 

[ca1ore]

I’ve used polycarbonate as lid material, usually 1/4”, and it had not warped at all. Neither LED nor T5 generate much heat, so I wouldn’t think that would be a problem.

 

[Reefinmike]

Thanks for the input ca1ore, i assumed my lighting would be safe over it however it wouldn’t hurt to be sure since i’m not familiar with the material. Before I permanently fixed my kessils I found out that they’ll quickly melt aquarium center braces and glass lid hinges. Glass never gets warm. I take it’s due to the color, not the material.

I’ll give some .220” a try, I think it wouldn’t be a bad idea to drill and tap the 4 corners to secure the sheet down. I’ll have a couple 4” wide cutouts to get my arms in the tank, a cutout to access the overflow, a bulkhead for the return, one for fresh outside air and another with a pvc tube slightly under the water level. It’ll be sealed pretty darn well. My household air drops the ph .4-.5. Dosing kalk isnt quite enough to keep the ph above 8, I have ridiculously low nutrients so my cheato isn’t doing much at all and outside air directly to the skimmer only raises ph ~.1. This is my last attempt to get the ph up

 

[cromag27]

it will most likely bow in the middle of it’s a solid piece.

 

[Reefinmike]

it will most likely bow in the middle of it’s a solid piece.

Cromag- Is this an assumption or something you’ve experienced? I only ask because you say “most likely”...

 

[ca1ore]

Polycarbonate will not warp as a result of moisture like acrylic, but it will sag like any material without adequate thickness or support. Depending on how large a piece you need, you will either need to go thicker or add struts. My tank came with 24”x24” poly covers. They sag by about 1/2” in the middle because they are only 1/8” thick.

 

[Lowell Lemon]

I manufactured Acrylic aquariums for over 30 years and provided 1/8" polycarbonate lids for the access openings. Never had a problem with warping. I also used them for covers and lids on trickle filters and towers in the 1/4" to 3/8" range again with out any bracing or warping. They will require you to keep them clean to prevent dust and films from transmitting light to the corals in the aquarium. In your case I believe your aquarium has a center brace from front to back and spans about 22" or more at its longest span. As such I would use 1/4" or .220 material for the lids.

 

[cromag27]

Cromag- Is this an assumption or something you’ve experienced? I only ask because you say “most likely”...

polycarbonate is not very rigid. if there’s no support in the middle then it will sag. i was the first to start manufacturing screen lids for our tanks. i’ve only had one person ask me to build them a lid that would be completely sealed. and that was to keep his pot smoke out of the tank. needless to say, i passed on that job.

 

[alton]

I used 3/16" Poly on my Crystaline 65 for almost three years with no warping. Dimensions are 36" x 20"

 

[Lowell Lemon]

polycarbonate is not very rigid. if there’s no support in the middle then it will sag. i was the first to start manufacturing screen lids for our tanks. i’ve only had one person ask me to build them a lid that would be completely sealed. and that was to keep his pot smoke out of the tank. needless to say, i passed on that job.

You could have just used "smoked" polycarbonate instead of clear....LOL.;Happy

 

[cromag27]

You could have just used "smoked" polycarbonate instead of clear....LOL.;Happy

nice!

 

[Reefinmike]

I’ve only had one person ask me to build them a lid that would be completely sealed. and that was to keep his pot smoke out of the tank. needless to say, i passed on that job.

Hahaha my tank isn’t in a constant fog however I certainly don’t make any effort to keep pot smoke away from my tank. I’ve been a reef aquarist for ~12 years, a reefer lover for 10 years and i’ve never seen a negative effect.

I know it sounds a bit extreme to completely seal off my tank but high co2 in my house severely depresses the ph. This seems like the most sound way to combat that by bringing fresh air over the surface water and through the skimmer. Kalk, refugium growth and co2 scrubbing media all seem like bandaid fixes.

Thank you very much for all the input from people with experience, especially the tank builders. I think I will go with .220” material and instead of one long cutout in each panel, i’ll have two 4x8” cutouts to help preserve the integrity.

 

[cromag27]

Hahaha my tank isn’t in a constant fog however I certainly don’t make any effort to keep pot smoke away from my tank. I’ve been a reef aquarist for ~12 years, a reefer lover for 10 years and i’ve never seen a negative effect.

I know it sounds a bit extreme to completely seal off my tank but high co2 in my house severely depresses the ph. This seems like the most sound way to combat that by bringing fresh air over the surface water and through the skimmer. Kalk, refugium growth and co2 scrubbing media all seem like bandaid fixes.

Thank you very much for all the input from people with experience, especially the tank builders. I think I will go with .220” material and instead of one long cutout in each panel, i’ll have two 4x8” cutouts to help preserve the integrity.

keep me updated. i’m curious how this pans out.

 

[Reefinmike]

Will do! I know the general consensus is “dont chase ph” however if I did nothing my ph would be 7.6. With fresh air to the skimmer it still gets as low as 7.8.

Everything grows and looks much better when i can keep the ph above 8.