Glass or Plexyglass top?

[Ace25]

Bottom line, I do own a PAR meter and I have tested both glass and eggcrate and I will tell you that eggcrate blocks MORE light than glass does... according to my PAR meter. If someone has any other REAL results to prove me wrong I would love to see them, otherwise I am going with the numbers my meter told me.

That said.. the CO2/gas exchange IS a valid concern and something one has to consider. If you have a sump on your setup though, from every tank I have seen with glass tops/sumps the ORP still falls within NSW levels. Without a sump/water export setup then I agree, sealed tops are not the best idea. Yes, I am a true aquarium geek and have digital PAR, ORP, and Phosphate meters I use to test my tank and others tanks with.

 

[BioHazard]

What about evaporation?

 

[Ace25]

Much less evaporation with glass tops, which isn't a good or bad thing. Just means you have to top off less. Glass tops do hold heat in more because of less evaporation so temperatures are a consideration. Again, if you have a proper setup, overflow, sump, and a chiller, then there is nothing wrong with a glass top. If you have a stand a lone tank then glass tops may not be the best option. Still, I run a glass top on my 29G FO tank right now, not completely sealed because I have a HOB filter on it, but it is 90% sealed and pretty much stand a lone and I have no problems with it nor do the 5 fish in it.

GregAW, with starphire glass, when talking about a top of an aquarium, isn't the most economical option. You really don't see benefits (clarity) of low iron glass like starphire until you reach 1" thick, less than that and it is extremely hard to distinguish between normal glass and starphire.

 

[kcress]

Ace I'd expect eggcrate to be quite restrictive. More so than any glass or acrylic so your test agrees with my expectation. That wouldn't be the same for a fine but open net.

Thanks for the info.

 

[thincat]

This is what I did.

 

[excuzzzeme]

Almost all of my tanks have glass under the light and it doesn't seem to be a big deal. Potential problems posted don't seem to exist for me. My fish are all healthy and my plants still grow. I have a good view of the tanks contents, which cause me to say that for the average person, Glass is not a detractor, but plexi-glas, polycarbonate, etc will scratch too easy to make it durable enough to warrant cost over glass.

 

[redfishblewfish]

excuzzzeme, you mention plants, but not corals….I’m talking corals, which use the UV side of the spectrum as well.

With my freshwater tanks, I agree, glass does not appear to impact the growth of my plants as well. Also, if you have a FO or FOWLR, then a glass top would be just fine. But when you start putting corals in the tank, quality of light is important. Again, if my little pea brain remembers the numbers correctly, glass cuts about 60% of important UV while polycarbonate only cuts 8%.

 

[excuzzzeme]

Hmmmm, guess I missed the part about corals, sorry. Since you intend to have jumpers I would likely go with acylic.

 

[Ace25]

Huh? I thought UV was bad. Hense the reason it is REQUIRED to run a UV glass sheild on all DE MH bulbs and all SE MH bulbs have UV shield build into the bulb/glass. Not sure where you are getting your information about glass tops blocking UV and it pertaining to coral health.

 

[redfishblewfish]

Huh? I thought UV was bad. Hense the reason it is REQUIRED to run a UV glass sheild on all DE MH bulbs and all SE MH bulbs have UV shield build into the bulb/glass. Not sure where you are getting your information about glass tops blocking UV and it pertaining to coral health.

To quote Carl Strohmeyer:

“A glass top is OK for most fish (although still not the best as they still do better with more UV light, in part due to an improved Redox Balance (ORP).
I recommend using a Polycarbonate top (if a top is even required) as glass block more than 60% of beneficial UVA rays. Polycarbonate only blocks about 8-10% (provided it is kept clean).”