Reducing evaporation with acrylic light fixture panels?

[Humble_Reefer]

Anybody ever use these to cover a frag tank? I have a 24x48 frag tank that I need to reduce evaporation on. My lights are at 50%, so Im assuming a mild reduction in par would be okay if I just crank up the lights to compensate.

 

[burnetb1]

It would be more expensive, but I would go the clear Plexiglas route. Just my personal opinion, but I think over time you would be unhappy with a lid you cant see through. I think these would work, but having a clear top will give you more predictable measures to set your lights to.

 

[Humble_Reefer]

It would be more expensive, but I would go the clear Plexiglas route. Just my personal opinion, but I think over time you would be unhappy with a lid you cant see through. I think these would work, but having a clear top will give you more predictable measures to set your lights to.

Good point. Probably worth the extra $50 in the long run...

 

[fishguy242]

hi use 3/8 glass won't bow easy to clean won't fog after time from lights jmo

 

[Biokabe]

Don't use Plexi (acrylic) for lids. Use Lexan (polycarbonate) instead. Similar optical properties, but acrylic absorbs water and will start to bow unless you get it cut unnecessarily thick. Polycarbonate doesn't absorb water, so it'll remain unbowed. It will attract dust and salt creep, but it doesn't have much effect on PAR (you lose maybe 10%, so just dial up your lights a bit to compensate).

 

[burnetb1]

Very good idea with the PC. Much better plastic.
I'm kinda kicking myself right now.... I work in the plastics industry.... lol I should know better.

 

[Semper.Reefing]

I am thinking about getting a sheet of clear PC for my 75 gallon as well as the sump to reduce evaporation. How often do you find yourself wiping them down?

OP did you go this route? Have any pictures or advice on how theyre doing?

 

[MikeTheNewbie]

Don't use Plexi (acrylic) for lids. Use Lexan (polycarbonate) instead. Similar optical properties, but acrylic absorbs water and will start to bow unless you get it cut unnecessarily thick. Polycarbonate doesn't absorb water, so it'll remain unbowed. It will attract dust and salt creep, but it doesn't have much effect on PAR (you lose maybe 10%, so just dial up your lights a bit to compensate).

Why not using using glass instead of polycarbonate?

 

[Doctorgori]

Don't use Plexi (acrylic) for lids. Use Lexan (polycarbonate) instead. Similar optical properties, but acrylic absorbs water and will start to bow unless you get it cut unnecessarily thick. Polycarbonate doesn't absorb water, so it'll remain unbowed. It will attract dust and salt creep, but it doesn't have much effect on PAR (you lose maybe 10%, so just dial up your lights a bit to compensate).

This post is spot on ... Different materials have different absorption properties (or whatever the word is)
Anyway, indeed whatever light passes through changes its spectral properties...
I wanna say FAMA or TFH had a table of different materials and their effects on PAR or Lumens or whatever it was back then
Basically you can’t just slap a piece of glass over the tank and not expect some loss of light

 

[Katrina71]

@cromag27 can probably point you in the right direction

 

[MikeTheNewbie]

I'm planning to design and build a lid for my 230 gal rimless peninsula.
While researching and quoting materials I found conflicting information.
The plastics store close by recommended acrylic for my application and I saw articles like this https://www.acplasticsinc.com/informationcenter/r/lexan-vs-acrylic
that seem to favor acrylic's properties over plucarbonate's for my application. Plus, I have seen acrylic tanks and never polycarbonate.
Nevertheless I have seen a few messages in R2R that state polycarbonate is better.
Can anyone elaborate on the benefits of polycarbonate over acrylic for aquarium lids?
Reference articles along with anecdotal evidence would be extra helpful.
Thanks

 

[fishguy242]

hi, unless 1" thick either will bow,even with supports,go low iron glass??

 

[MikeTheNewbie]

They recommend 3/8.
A 4 by 8 sheet of acrylic goes for $150 and polycarbonate for $250.
I'm thinking about splitting the lid in 3 sections and using some sort of double layer for the frame to improve rigidity, specially for the middle section.
I plan to make each section convertible between mesh and acrylic lid so I can control evaporation.
I'm not confortable working with glass and I think the intricate design will require plastic.

 

[ca1ore]

Don't use Plexi (acrylic) for lids. Use Lexan (polycarbonate) instead. Similar optical properties, but acrylic absorbs water and will start to bow unless you get it cut unnecessarily thick.

Was about to make this very point!

 

[Billdogg]

Due to the greatly reduced oxygen exchange caused by any solid top, I got rid of them completely years ago. Sure, there is some evaporation, but at least IMO it is a small price to pay for a healthier tank. In addition, because anything you cover the tank can and will affect the amount of useable light that reaches the tank, I find that anything more than a simple screen top just costs me more in lighting - both upfront (having to purchase more powerful lights) and long term(your electric bill)

 

[MikeTheNewbie]

Thank you guys for the feedback. I was worried about the evaporation making my basement more humid than it already is but with winter upon us I think I won't mind the extra humidity. I've been running Neptune ATO without issue.
Thanks to your feedback I have changed my mind, now I'm planning to make a DIY mesh top with polycarbonate frame.