Evaporation control & LED lighting

[lysaer]

Hey guys, I did a search and didn't find anything really specific to this question, so... here goes.

Currently, in my 55g tank, I'm seeing a 3-5g evaporation rate daily...which will only increase as the summer comes on because my house gets really warm during the day so I know that's going to increase. Right now, my tank has no cover. I have LED lights hanging over it.

In the next couple of weeks, I'm going to be setting up a 40g Breeder w/ sump in a nearby location, and moving all my rocks/sand to it and starting things over. I'm really concerned about the evaporation from both the tank and sump-to-be over the next few months, and am considering putting a glass top on the tank. I don't know how this will affect the PAR for the LED lights hanging over it, though. I have Wellpar (chinese black box, more commonly) LED lights that will be mounted 12" above the tank. My concern is if I add a glass top to the tank, how much of that light will be reflected and how much *actual* par can I count on at 6"/12"/sand level of the tank?

I've seen diagrams that relate basic LED PAR levels at various depths, but those seem to be based on a no-top tank. I'm working on including an ATO setup for everything but it will be <5g, at least for the first few months based on my expected setup, so my worry is that it will get emptied on a daily basis and add a step to my morning routine. That is to say, add the expected amount of salt to the ATO resevoir and leave my RODI filter running all day every day (40g/d estimated) which might overflow something somewhere while I'm at work unless I also incorporate a float switch for the RODI system which I don't have in my current plans.

So the root question is, does anyone have experience with LED lights over a glass-topped tank and can you give me examples of both the effective PAR you have experienced as well as your evaporation rate with the top?

I hope this makes sense. :)

 

[pickupman66]

So, as long as the glass stays quite clean, it won't effect the LEDs much. But keeping it clean will be a chore. That is a lot of evap. You must be in an arid climate. I lose about a gallon per day on my 66 gallon rimless system

 

[MarcWeaver]

If your house gets hot, a glass cover may cause your tank to overheat, unless you position fans blowing over the surface of the sump, which defeats your intended purpose. I used to have glass under my LED's (not over the tank) and even when the glass got a little dirty, PAR readings were only around 10% lower.

I am also a chinese black box user with 6 lights 9" over a 220 gallon tank with no glass under them now. I run blue at 80% and white at 45% and am growing SPS coral as low as 29" under the light. The PAR readings ranged from 500 a foot down to 150-200 near the bottom, and that was with water spots all over the glass covers on the LED's themselves.

As said previously, that evap rate is very high. I only lose 3-5 gallons per day in my 325 gallon total water volume system. I'm not sure what to tell you, other than a glass cover, to help with that evaporation rate, though.

 

[naptalene]

In Joburg we get higher evaporation rates in Winter as the air is waaaayyyyy drier than our summers. I literally get double the evaporation in winter. You might ( hopefully) get a nice surprise if you get summer rainfall.

If you completely close the top maybe run an external air hose to the skimmer so you get lots of fresh air into the system ( watch out for pesticides etc.)

 

[lysaer]

Well, I live in the heart of "It's not the heat, it's the humidity!" so it's not very arid here. The humidity in my house stays around 45-50%. Tank water temperature only fluctuates between 26.5 and 27.5 degrees celsius as far as I've seen.

My skimmer actually does have an external air hose but it's getting moved into the new sump soon. To be honest, the evap problem may be taken care of when I get the new system set up. Thanks for the input. :)

 

[naptalene]

May it be most awesome lol:)

 

[saltyfilmfolks]

you will lose little to nothing with light through glass. See Lux meter.
I have to clean mine occasionally. really it only me who gets them messy.
temp is a thing to look at. I have a pretty simple set up and with t5 & led in a canopy and pumps my tank is rarely above ambient temp.

And yea the evap is from having no lids.

In summer I have thick acrylic with fans for cooling. Easy diy.