Will my glass lid obstruct the light?

[Pistondog]

That's not the same. Cloud cover considerably denser than water droplets. Do you have science backed assumptions on this or just an assumption? Easy enough to take PAR readings at home with and without condensation. Perhaps someone has or can. Won't be having a PAR meter for a few months.

From the OPs pics, the condensation on the lid is light scattering which would reduce transmitted light.

Edit vintage reefers pic

 

[Reef_puck]

IME the glass tops (at least the Aqueon) ones do block a substantial amount of PAR. In my 90 running Radion XR15 blues . Using PAR meter I test all over the tank with different intensities with the glass tops on and with them off and I witnesses about a 50% reduction in PAR.

 

[GARRIGA]

From the OPs pics, the condensation on the lid is light scattering which would reduce transmitted light.

Edit vintage reefers pic

Would without proof is an assumption and having been one to grow plants with lids I can assure you light appears to get through just fine. Visually not seeing a difference in light intensity using vs not using although only way to be factual is using a PAR meter otherwise just based on assumptions. Plus think about what a water droplet consists of. Water. If light is getting through water then why not a water droplet?

 

[GARRIGA]

IME the glass tops (at least the Aqueon) ones do block a substantial amount of PAR. In my 90 running Radion XR15 blues . Using PAR meter I test all over the tank with different intensities with the glass tops on and with them off and I witnesses about a 50% reduction in PAR.

That's different than condensation. Material used has a large effect on light transmission.

 

[GARRIGA]

Google "greenhouse light transmission". What I did when selecting tops for my planted tank experiments.

 

[Pistondog]

Would without proof is an assumption and having been one to grow plants with lids I can assure you light appears to get through just fine. Visually not seeing a difference in light intensity using vs not using although only way to be factual is using a PAR meter otherwise just based on assumptions. Plus think about what a water droplet consists of. Water. If light is getting through water then why not a water droplet?

The shade of a tree has less par than no shade, some light is blocked by the leaves.
The droplet scatters light because of multiple air water boundaries where the light is refracted or bent.. Some light gets thru, but not all as evidenced by the visible light on the droplets on vintage reefers top. If some is reflected back to your eye, it is not getting thru to the corals or whatever is in the tank.

 

[gbroadbridge]

Plus think about what a water droplet consists of. Water. If light is getting through water then why not a water droplet?

Physics.

Water droplets have optical properties unlike that of air.
Each droplet will refract light slightly differently and will also reflect light from the air/water boundary.
It results in much higher light attenuation than a piece of optical glass, for instance.

 

[GARRIGA]

Physics.

Water droplets have optical properties unlike that of air.
Each droplet will refract light slightly differently and will also reflect light from the air/water boundary.
It results in much higher light attenuation than a piece of optical glass, for instance.

Are we splitting hairs or actual material detriment to PAR that has been verified with actual meter testing?

 

[GARRIGA]

There is a minimal effect on par. I’ve tested with and without the lids. Mesh affects par slightly less. Eggcrate lids affect par much more. With glass/polycarbonate it’s a non issue. It doesn’t matter if a spot is 143 or 149. The difference with the lids is negligible.

Seems to be a raging concern with water droplets. Noticed your pic full of water droplets. Fair to say you PAR test based on solid lids full of water droplets? Hoping to put this issue away although I doubt it.

 

[PotatoPig]

My 2c: I have glass panes on my 75g tank. When I tested with a par meter from the LFS I got about 10-15 less PAR (down from 150-100 range) under the panes.

IME: The heat from the LED lights also prevents condensation in the vicinity of where the bulk of the lights goes through the glass.

That said - I’m changing to a mesh lid this week. Two main reasons:

1. The glass reflects a lot of light (for a room, not for corals) up up at the walls and ceiling around the tank, which I’m trying to cut down.

2. The panes can be cumbersome to pull out for maintenance and I don’t like the consequences of dropping one.

Another aspect is top-down views are much better without the glass in there.

 

[GARRIGA]

Used glass tops in the 80s and never will again for the same reasons noted. Fear of dropping. Plus polycarbonate allows better light transmission. What I've used was twin wall that is used in green houses. Not sure what the custom top builders use but just know glass not in my future plans.

Don't recall my tops reflecting light. Including the glass panels used in the 80s. That would be something worth considering as a negative although some might like the pool like reflections.

 

[VintageReefer]

Seems to be a raging concern with water droplets. Noticed your pic full of water droplets. Fair to say you PAR test based on solid lids full of water droplets? Hoping to put this issue away although I doubt it.

Yes I par tested with apogee
I would argue negligible results. 8-10 par approx

Amount of droplets can vary also . I took A pic just now. Have not cleaned these lids in over 2 weeks

 

[Spare time]

I am pretty sure Dana Riddle did a measurement and found the glass lids can block up to 15% of the light overtime depending on how clean it is.

 

[VintageReefer]

Also I do not have any reflection from these polycarbonate panels

I’ll also remention, the droplets accumulate, then when the drop gets large enough, it drips back in the tank and the spot is clear again. It’s self cleaning, constant process, going on round the clock. There is no salt creep because new condensation washes any away. Obviously if I spill water on top of the lid and don’t clean it, it will dry and form salt creep just like any other surface. But that would be my fault and a result of laziness

Cleaning these is easy, I stand vertically in my sink and hit them with my kitchen sink sprayer. They are much lighter weight than glass and easy to carry

I’m not going to name bash any company, but I will say this.

My mesh lid on my 15g water box was over 100$ and gets salt creep all the time. It ends up on the mesh. All of the mesh. Looks horrible. Just happens. Evap is also a nightmare on that tank even with a 5g ato bottle. Doesn’t last a week.

On my 75g with the poly carb lids however I only evap 1g every 7 days. And there is no creep. If I don’t spill, I can go weeks and weeks without needing to clean them. These custom made polycarb panels were 40-50$ each

 

[PotatoPig]

Also I do not have any reflection from these polycarbonate panels

What type of panel do you use? Curious about thickness and so on.

 

[VintageReefer]

What type of panel do you use? Curious about thickness and so on.

My lid builder (who I recommend) is in post 5. The panel is a polycarbonate which will not bow over time like acrylic does. I would say it’s approx 1/8” maybe a little more

 

[GARRIGA]

it’s not just the condensation but the heat trap…
just one of many reasons why most just usenet tops

Which boggles my mind since most also run heaters.

 

[VintageReefer]

Which boggles my mind since most also run heaters.

I feel this was more of an issue for tanks running halides in close proximity

My heater still runs with a lid, it just runs less

 

[GARRIGA]

I feel this was more of an issue for tanks running halides in close proximity

My heater still runs with a lid, it just runs less

That's my point. Less heater needed with solid lid vs mesh. Along with less evaporation. Easy enough to get a few more PAR and most lights today ran at lower intensities to boot. Still learning about DLI but that might be an option for those unable to squeeze a few more PAR. Something I believe I was doing in the 80s inadvertently because tank lights on when I woke and off near sleep or when parents turned them off if I was staying out late. My oversized anemone seemed fine with the inadequate lights I was able to afford at the time.

Reason I stayed away from halides in the 80/90s being heat generated along with mounting concerns. Back then seemed most ran chillers, too. Another item I couldn't afford.

 

[Ben's Pico Reefing]

I live in Florida and keep house at 73. I have heater to keep temp up. I have a full glass lid custom ordered from Amazon. I have no issues with light even with the water building up on internal of lid. I also have the lid that covers the back chamber.

I have the glass cut and beveled to sit on top of the tank (rimless).

However, I recommend running an air pump to ensure proper gas and oxygen exchange if sealed fairly well. I have no issues with evaporation.