Open top tank or closed?

[Yugang]

My last high tech planted tank was closed top, my current tank is open, my next tank will be closed top again.

I could see the following considerations when choosing for open versus closed

• One may find open top look/fit better, or find closed look/fit better in the room where it is placed
• Accessibility for maintenance
• Safety for jumping fish and shrimp, adventurous snails, pets, children
• Humidity and evaporation
• Temperature (Insulation/energy savings or the lowering temperature during summer with circulation and evaporation)
• Space under closed top for hiding technology

With regards to how open/closed planted tank affects gaseous exchange, and tank/livestock/plant health there is very little to be found on fora or commercial sites. There may be one or two opinions, but I have found nobody who reported issues with a closed tank that had to be resolved with opening or ventilation. I have done experiments for 6 months with a nearly perfectly closed tank (using evaporation as a proxy for gas exchange, more than 95% reduction versus open tank), and have never seen any ill effect on plants fish or shrimp even when injecting more than 1.5 pH drop CO2. One could even make the argument that closed planted tank, a net oxygen producer during the day, will keep the oxygen better in, which will benefit fish and microorganisms, and could be helped with an air pump at night. So in summary, from a tank health perspective the open/closed discussion almost seems a non-issue?

So what is your preference, and why?

 

[Count Krunk]

Open, screen top. But perhaps glass top would be better? Cut down on evap a bit. System would still have a sump so plenty of gas exchange there.

 

[Ed Wiser]

All depends on animals in the tank. I have rainbows so I have a custom screen lid made for the tank.

 

[BigWave]

Ive had both. Even still have a MarineLand tank that has a top. Cant really do anything with it. Bought it way back when I didnt know anything about the hobby. There is no easy way to modify the 15w T5s that are in the hood and keep everything waterproof.
So open top all the way for me. If you have jumpers get a screen. They make all sorts of fancy ones now days.

Side story...... I had an Aqueon 50 gallon with the glass lids back in the day. Had DIY Shop lights hung over the tank. Dont remember exactly but about 25 watt screw in bulbs. Came home one day and there was glass all over the floor and inside the tank. The shop lights got the glass lids so hot that when the water condensation from the tank hit the lids they cracked and fell in and over.

 

[Yugang]

This happened earlier today, an unusual sight in Hong Kong. I guess we have one more vote here for open tank.

For me both open and closed could work. What I like most with closed is control of humidity, which is an issue in our climate, as well as the possibility to experiment and control CO2. I made a transparent acrylic tank lid, that I sometimes use for a couple of weeks or months. My lights are just a few cm above the water, because I don't like the glare of higher lighting units, but then do compromise the experience of an open tank a bit. My next tank will be closed.

 

[FrankZ]

This happened earlier today, an unusual sight in Hong Kong. I guess we have one more vote here for open tank.

For me both open and closed could work. What I like most with closed is control of humidity, which is an issue in our climate, as well as the possibility to experiment and control CO2. I made a transparent acrylic tank lid, that I sometimes use for a couple of weeks or months. My lights are just a few cm above the water, because I don't like the glare of higher lighting units, but then do compromise the experience of an open tank a bit. My next tank will be closed.



View attachment 4254

That’s a nice tank yugang! Did the pigeon bring you a message? I see a band on it’s leg

 

[riioKen]

I had an old closed top tank. It was a nightmare to add everything (external canister, lights, fans, co2, I hated it).

Now I have a open top, and in the near future I'll buy some jumpers, instead of an acrylic top i thought in something like mosquito net or idk how is called in English lol (the net placed at the windows in a house lol).

 

[Count Krunk]

I had an old closed top tank. It was a nightmare to add everything (external canister, lights, fans, co2, I hated it).

Now I have a open top, and in the near future I'll buy some jumpers, instead of an acrylic top i thought in something like mosquito net or idk how is called in English lol (the net placed at the windows in a house lol).

That works. Screen netting, 1/8" is what i like to use. And i much prefer clear over black.

 

[Mr.Shenanagins]

This happened earlier today, an unusual sight in Hong Kong. I guess we have one more vote here for open tank.

For me both open and closed could work. What I like most with closed is control of humidity, which is an issue in our climate, as well as the possibility to experiment and control CO2. I made a transparent acrylic tank lid, that I sometimes use for a couple of weeks or months. My lights are just a few cm above the water, because I don't like the glare of higher lighting units, but then do compromise the experience of an open tank a bit. My next tank will be closed.



View attachment 4254

How many squirts of fertilizer did that provide?