Does acrylic filter out any important parts of the spectrum?

[deepseadan]

I have a section of my tank which I want to drop the par a bit. The simple way to do that would be to take a piece or two of acrylic and put it between the fixture and corals (above the water obviously). Does anyone know if doing that will filter out any part of the spectrum that will negatively affect my sps. The fixture is as high as I can hang it and I can't drop the par any other way. It's a Hamilton Cayman sun fixture with a radium 250 being driven by a lumatek.

[karsseboom]

I wouldnt think so.

[Epicreefer]

A better method would be to use some screen of some kind, from a good source they will tell you the % transmittance, or space between the material vs the material. This would give you a clear idea of how much light your cutting out. An interesting thing about acrylic is it actually magnifies light due to the change in material that light is traveling through. That's why things look bigger in an acrylic tank. So on one side your focusing light to a narrower area and on the other your blocking some by passing it through a dense but very clear material. Kind of fighting yourself and I would have to do some calcs but I think it's about null effect on the majority of the tank, the acrylic is just too clear, a bug screen is probably cheaper and would reduce light more, around 10-20%.

[reefSTC]

tagging alone, wondering about this as well...

[deepseadan]

Originally Posted by Epicreefer

A better method would be to use some screen of some kind, from a good source they will tell you the % transmittance, or space between the material vs the material. This would give you a clear idea of how much light your cutting out. An interesting thing about acrylic is it actually magnifies light due to the change in material that light is traveling through. That's why things look bigger in an acrylic tank. So on one side your focusing light to a narrower area and on the other your blocking some by passing it through a dense but very clear material. Kind of fighting yourself and I would have to do some calcs but I think it's about null effect on the majority of the tank, the acrylic is just too clear, a bug screen is probably cheaper and would reduce light more, around 10-20%.

My tank is acrylic and I was thinking about using the old tank covers ( I replaced them with new clear ones a while back) which are somewhat foggy and scratched from years of use. On my par meter they drop the par around 50, but I don't want to filter out the good stuff. As much as I don't want to, I may have to drive my center radium at the regular 250 watt setting instead of the hqi setting. Hopefully it destroy my bulb.

[Epicreefer]

The foggy acrylic will definitely do a lot more than new clear stuff. My recommendation with the screen was mostly because you can get a definite % of how much your reducing light. It also doesn't remove any spectrum more so than the others. My boss built an acrylic lid a few years back to reduce evaporation and I think he was pretty happy with it.

I stumbled across a thread a few days ago about covers to reduce evaporation. Some people said they saw significant increas in growth when they took the covers off but couldn't determine if it was from light or gas exchange. If you don't like it after a few months you can always take it off, you aren't going to kill anything by starveing it of light without some knowticable effects much earlier. Also the lenses on LEDs are acrylic so with that in mind I would assume acrylic isn't going to take out specific wavelengths corals need.

[deepseadan]

Originally Posted by Epicreefer

The foggy acrylic will definitely do a lot more than new clear stuff. My recommendation with the screen was mostly because you can get a definite % of how much your reducing light. It also doesn't remove any spectrum more so than the others. My boss built an acrylic lid a few years back to reduce evaporation and I think he was pretty happy with it.

I stumbled across a thread a few days ago about covers to reduce evaporation. Some people said they saw significant increas in growth when they took the covers off but couldn't determine if it was from light or gas exchange. If you don't like it after a few months you can always take it off, you aren't going to kill anything by starveing it of light without some knowticable effects much earlier. Also the lenses on LEDs are acrylic so with that in mind I would assume acrylic isn't going to take out specific wavelengths corals need.

That's true about the led lenses being acrylic......I didn't think of that.