Glass canopy or no canopy?

[hwofnt]

Tank cover: yay or nay?
What do you think about covering the tank to reduce evaporation?

I read on the web that reef tank should be left uncovered, mesh only for jumping out fish. This means the daily evaporation for 90-125g tank be 1 gal, quite a lot. Also splashes made by fish lead to lights' protective cover be covered with salt and require frequent cleaning.

I'm curious how this works for any kind of tank - FW or SW. If air pump is used, drops of water reach the lamps cover as well.

Which covers are better?

I'm using the Perfecto glass canopies (black line along the tank) on some small tanks and don't like it much: the shade creating line is right under the light, hard water dries on the glass right under the light again, reducing class clarity and worsening overall looks.

2 mm Lexan (polycarbonate) is too thin to hold own shape, even if siliconed to the metal frame, free standing it just breaks at the ends. Condensation drops underneath due to temperature differences reduce amount of light passing through it.

Recommended somewhere as a cheapest tank cover prismatic thin plastic cover, that is sold near eggcrates in hardware stores, is obscenely brittle, breaks even during storage, and reduces amount of passing light even more.

Any thoughts?

[Carl]

I prefer polycarbonate, but as you noted flexing is a problem. The problem with glass is glass blocks more than 60% of beneficial UVA rays, while polycarbonate only blocks about 8-10%

An open tank is best, but the amount of work it creates can be considerable, as well the wet salt residue can be a fire hazard around lights if not properly protected.
With open tanks I ran beads of silicone around areas that I was concerned with (even if it meant more work in removing bulbs, etc.) as this would repel some salt, but more importantly lessen fire hazards with was always my #1 concern (I used drip loops and other fire preventative methods as well).

I honestly do not have a best answer, as I used different methods myself depending upon the specific tank, amount of spray, and tolerance for "mess" of myself or a client.
IMO, this is an area of reef keeping with no easy answer that I know of (with fish only or FOWLR I used a glass or acrylic lid, provided the best lighting I or the client could afford and did not worry about it)

Carl

[hwofnt]

Thank you!

[parker002]

I have to bump a thread that's almost a year and a half old but I'm in almost the exact same situation as the OP - I have All-Glass glass versa tops and the plastic "hinge" down the middle casts a horrible shadow right in the middle of my tank.

I like the thought of polycarbonate from a light penetration standpoint but even the manufacturers of such material say it won't hold up well. Not only does it warp easily but it apparently yellows over time when exposed to heat, such as the kind that would be generated by my T5 lights.

I realize the best answer from a lighting standpoint is no lids at all but it's so dry here in winter, I'd have to do water changes every 3-4 days to avoid excessive evaporation.

[Carl]

I like the thought of polycarbonate from a light penetration standpoint but even the manufacturers of such material say it won't hold up well. Not only does it warp easily but it apparently yellows over time when exposed to heat, such as the kind that would be generated by my T5 lights.

While warping is definitely an issue (I have always used extra braces with polycarbonate tops), I have never had an issue with yellowing and this included lights that produce more heat than modern T5 lights.

Carl

[parker002]

Is warping an issue if the sheets are only 24x12?

I have an Aqueon 55G and it has a midline divider, so instead of needing one 48-inch lid, it needs two 24" lids.

For example, today I have 2 All-Glass Versa-Tops which measure 23-1/8" x 9-1/2" (without the back plastic strips).

EDIT: How thick should the sheet be? Obviously thicker sheets would reduce warping but also increase light diffusion and especially cost.

[parker002]

Would something like this work?

www.grainger.com/Grainger/LEXAN-Sheet-Stock-1ETP2

And I know they banned Lexan for use in stuff like baby bottles because of BPA leeching, is this a concern with using it for an aquarium?

[Carl]

Yes & No

This appears to be the correct material, but I used about twice this thickness (& even then it was still rather flexible, which is the only major undesirable attribute of polycarbonate I have witnessed from rather extensive use during my aquarium maintenance days)

Carl

[parker002]

Oh, I read it wrong - it's 6/100 of an inch think, not 6/10!

This one is a bit more expensive but it's also .177 thickness so almost 3 times thicker than the first one I linked.

www.grainger.com/Grainger/LEXAN-Sheet-Stock-1ETP5?Pid=search

[parker002]

Hey Carl, I need some urgent help here on this.

I was cleaning my tank today and squatted down to pick something off the floor, catching the seat of my pants on the corners of my Versa-Tops (they were in a 5G bucket of course), SNAPPING THEM BOTH CLEAN IN TWO.

I'm not spending $25 to buy 2 more when they're so much worse than the Lexan but I really need to go to like Lowe's or Menard's tomorrow and get it taken care of as quickly as possible.

Thanks man, I really appreciate it.

[parker002]

Here's a 28x30 sheet at Lowe's for $35 that's .093 inches thick so almost 1/10th of an inch. I'm hoping they can cut it to size for me to save me the trouble.

www.lowes.com/pd_60407-1638-1PC0028A_0__?productId=3143411&Ntt=lexan&pl=1¤tURL=%2Fpl__0__s%3FNtt%3Dlexan#BVRRWidgetID

EDIT: It says in the specs that it BLOCKS harmful UV rays. I thought it was desirable because it DOESN'T block them?

[Carl]

This should work (it is close to the 1/8 inch I used)

As for the specfications, it says UV stabilized of which the function is to protect the substance from the long-term degradation effects from light, most frequently ultraviolet light (which goes against this comment by others giving "advice: "it won't hold up well. Not only does it warp easily but it apparently yellows over time")

Carl

[parker002]

OK, awesome. I suppose it's going to be superior to glass from a spectral perspective and I have to make the change now, so might as well jump in with both feet!

Thanks again!

[parker002]

I once again had to be reminded a valuable lesson. After spending all afternoon in the metro at the big box stores hunting for polycarb sheets that would work, I gave up and came home.

This morning, I called the mom and pop glazier and they not only have 1/8-inch polycarb sheets, they'll cut it to the exact 23"x10.75" sheets I need and they're CHEAPER than any of the stuff I looked at yesterday.

The good news about using the 1/8-inch is that I can use the vinyl back-strips off of my glass tops so I don't have to have them do any elaborate cutouts for my filters and stuff. I can just slide the strips on the back and I'm done.

[Carl]

I once again had to be reminded a valuable lesson. After spending all afternoon in the metro at the big box stores hunting for polycarb sheets that would work, I gave up and came home.

You won't get any argument from me!

I cannot stand Lowes or Home Depot; when in LA I used a local Ace that even when higher in price the service was worth it.
In fact with Lowes I can still provide many horror stories just from what they tell customers in their incompetent pond care department.

For Polycarbonate I used a specialty business; Paragon Plastics.

Carl

[parker002]

Yeah, my in-laws Koi pond experience started with a trip to Menard's. They brought in a pro a couple years back and everything has been peachy since then.

[parker002]

So I've had my 1/8-inch Lexan for 2 days and already they're starting to sag severely.

Any recommendations?

[Carl]

Feb 17, 2011 7:43:31 GMT -5 parker002 said:

So I've had my 1/8-inch Lexan for 2 days and already they're starting to sag severely.

Any recommendations?

Usually they sag immediately, so when I have placed these on a clients tank I would use braces and never go further than 18 inches between braces.

Carl

[parker002]

Braces along the length, left to right? Or braces along the depth, front to back? I don't have any extra Lexan to brace with so anything I do has the potential to end up in the way of my light.

I thought about finding rigid glass edging and putting it on the front and back edges and see if that would help.

[Carl]

Braces along the length, left to right? Or braces along the depth, front to back? I don't have any extra Lexan to brace with so anything I do has the potential to end up in the way of my light.

I have used braces both on length and width, but 80% of the time via the width of the polycarbonate.

Usually I used glass (strips) as a brace, but sometimes I would use whatever material was on hand at the time.

Carl