What's with the trend for 'Open' tanks?

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can't you just use RO water to top it off and then do the water change?
that's a real hassle though and one of the reasons why i'll never keep open tanks.
You could and, to be honest, evaporation shouldn't make too much of an issue...PROVIDED you're aware of the potential effects of it and what it can do to your tank parameters.
 
can't you just use RO water to top it off and then do the water change?
that's a real hassle though and one of the reasons why i'll never keep open tanks.
I top off evaporation with RO/DI water in my FW tanks, but I also do weekly water changes.
 
My 7.1 nano tank is nominally topless, but with the two HOBs (one small, one larger) and most especially the two lights that hang across the rimless tank, most of the surface area of the water is covered. My betta hasn't jumped yet (and perhaps is too fat, gravid, and lazy to do so). Even the hyper ember tetras stay in the mid-column. As my tank is only about five or six weeks old, I do a lot of water changes anyway, so any evaporation gets handled in the next change.
 
From my experience of aquariums in the late 60s, the 70s and 80s, tank lids were always, ALWAYS, considered to be essential, especially for tropical tanks.
Not only did the lid hold the lighting, be it bulbs or fluorescent tubes, but it helped reduce evaporation, minimised fish loss through jumping and, perhaps most importantly, it stopped dust and household airborne contaminants reaching the water surface.

Today, I see this popular trend for open tanks and, whilst I can appreciate the aesthetics of such a tank, I'm wondering about jumping fish and those aforementioned 'airborne contaminants'?
The increased emphasis on plants is, as far as I'm concerned, a Good Thing and I do like those tanks with the plants growing up and out of the water.
I can also appreciate the nice lighting now available and the ability to get that 'different' view of the tank from above...although I suspect that might freak the fish out somewhat, as a potential predator suddenly appears above, casting its predatory shadow. ;)
Another factor with the light would be an actual reduction in the control of the light spectrum entering the tank. With a lid and modern lighting, the majority of the lighting can be controlled, with ambient lighting only entering from the sides left clear. Without a lid, ambient lighting enters from all five sides.
I can also appreciate the visual impact of a clear glass box, with colourful movement inside it, with visible frames and equipment kept to a visual minimum, although, again, I question the effect of such an open arrangement on the well-being of the fish.

Do those of you who have such tanks use a glass cover and, if not, how do you stop your fish jumping ship, minimise evaporation and stop airborne contaminants?
In brief, I needed riparian pants for nitrate reduction. I created this "bamboo forest" because the inhabitants have historically uprooted or destroyed every aquatic plant I've tried and eat floaters like their brine shrimp! In particular the tank that will see this has Oscars and pacu's in it such that anything but these plants were knocked down or uprooted.

While this approach might not appeal to everyone nor might it be useful for a tank with totally submerged plants but if your tank has above water growth or even uses riparian plants, this worked really well for me as an 'invisible replacement tank lid' and although the one pictured is white, clear versions of the cover grids are available. These are plastic lighting grids used in commercial light fixtures and are less than $10 at any Home Depot or Lowes.

The grid easily cuts to the exact size of your tank and totally supports the plants above the water and prevents jumpers and keeps the plants rooted and in place should you have any large, crazy fishes like pacu's that crash into everything when excited.

I should add that this particular setup dropped a 40ppm nitrate tank to a 5ppm nitrate tank in just 2 weeks after planting them. Worth a mention but you'll get the most nitrate reduction via plants by using terrestrials although many aquatic plants do this as well but not as efficiently. Most aquatic plants seek ammonia before nitrate due to their evolution in lower light (light penetrating the water being weaker than direct light above the surface) as direct use of nitrates require more light for photosynthesis. But there are a lot of exceptions but this worked wonders for me. A small fish can't fit through the grids and not even a 14" Pacu can jump out!
 

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I don’t get the trend for open tanks either. this is personal preference, but it Really bugs me when I can see the top of the water line. I’m just returning to the hobby and currently running just one nano with a glass cover, but back in the day I always had tanks with proper hoods and always made sure that the water level was 1 cm or so above the bottom of the hood so I couldn’t see it. Just my thing. However, any open top tank is going to get dust entering it, it’s just a fact of life. My nano is in a room we rarely use. Usually, it’s just me going in there to watch my own tv programs. Even so, the glass top has always got some dust on it. If the glass was not there, the dust would be in the tank. As I get more tanks I’ll probably stick with glass covers for nanos, but my “proper“ tanks will always have full hoods.
 
I must say I haven't read all of this. But a lid is really important on a tank. It keeps the fish in and stops the water getting into your house. I have had several tanks that were open and I really loved them. I like the fact you can put your head over the top of the tank and have a different view. I also loved the fact that plants would grow out of the tank and flower. My African Butterfly fish or my Killifish wouldn't have been have as cool with a lid on their tank. But you need to be careful and think about what you want and your fish need.
 
Also not a fan of open aquariums.....less mess, less Houdini attempts by the hooligans and nowhere near as often topping up the water levels with a lid on it.

I also hate rimless aquariums too, give me the extra strength & security of a rim any day of the week, a lounge tsunami is not a pleasant experience especially when you wake up in the morning and go for a paddle in the lounge and it takes a while for the braincell to understand why the carpet is soaking wet when you're still half asleep....
 
Most of my tanks have been open top for various reasons. There are pro's and con's and it's not suitable for all tanks and situations.

My planted tanks generally were heavily planted with plants growing out of the water. The fish where normally mid/bottom tank dwellers and not really known jumpers so I left them completely open. Never had issues with fish jumping but the tanks had a lot of plant cover. It also made it quicker to do a quick trim up with long tweezers/scissors as I could literally pick them up, snip, snip and job done.

My reef tanks were open topped to maximize lighting and to allow evaporation to help keep the temp stable in the summer. However these often did have fish in that were very jumpy so I would use eggcrate to put in as a barrier. I did lose one fish that "maybe" got past the eggcrate. However I think what it actually did is manage to get itself into the sump tank and jump out from there.

Getting dust and stuff in the tank. Not a big deal in my opinion. As long as you aren't spraying stuff around that is harmful to aquatic life a bit of dust wont do any harm. You literally have poop inside it, a bit of dust is fine. If there is something in your environment that is creating dust that may be harmful for the fish it is probably harmful to you as well so you have bigger problems to worry about,

Evaporation can be a big deal. On my bigger tanks in the summer I used an auto top off unit and used to burn through quite a lot of RO water to keep it topped up. That is good for the tank as it helps cool it. It's not good for your house though as all that water is going into your air and can cause damp problems. Not such a big deal with smaller tanks but 100G+ tank can chuck a lot of moisture into your living environment.

Ambient light, again not a big deal IMO. If you have enough light hitting the tank that having the lid out of the way is going to effect it then you already have too much light hitting that tank.

All the said my current tank I'm just setting up will have a lid on. It's in a busy living room with a 4 year old so more chance of a fish getting startled and jumping or something accidentally getting thrown into it.
 
The first paragraph of post #1 contains the issues which should be of concern to every hobbyist. One thing not mentioned though is non-fish related...all that evaporation is damaging the structure of the house. When that much evaporation occurs in a room, it goes into the walls and ceiling. Similar to a bathroom with no circulation
There’s not enough evaporation going on to significantly affect a house’s structure. My houseplants surely do appreciate the added humidity though.
 
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I top off evaporation with RO/DI water in my FW tanks, but I also do weekly water changes.
Is there not a danger of messing up your water hardness and therefore PH by adding RO water with no buffering? Over time there is maybe potential to drop your PH buffer capacity enough that you will start getting wild PH swings.

I could be wrong (it happens often) but in my head:
You have a tank with tap water around say 6KH. You top up with RO water and that maybe drops it to 5.8KH. You then do a water change with tap water and that brings you buffer back up a bit but maybe not right back to 6KH. Over time your KH drops a little bit each time you top up and then eventually gets to a point where your PH can start bouncing about.

A SW tank isn't bothered by this because it has a lot more stuff to act as a buffer but I believe (and again I could be wrong) that in a FW tank it's not quite the same.

I know in the past when breeding softwater fish I have managed to drop KH and then PH quite rapidly with just small amounts of RO so not sure I would want to put it directly into my tank.
 
I have an open topped axolotl tank. It is half filled so he can't jump out, and has no lid so there can be evaporation and keep it cool enough for him. It is in my bedroom, and there is hardly any dust because I don't go in there much, I vacuum regularly, the windows aren't opened regularly, and the door stays shut so the dogs don't get in there
 
I have an open topped axolotl tank. It is half filled so he can't jump out, and has no lid so there can be evaporation and keep it cool enough for him. It is in my bedroom, and there is hardly any dust because I don't go in there much, I vacuum regularly, the windows aren't opened regularly, and the door stays shut so the dogs don't get in there
I strongly suggest that you get a lid and use it.

Axie's are fantastic jumpers....my silly lad used to jump alot once mature and he would headbutt the lid clean off its housing. They don't just just cos of poor water chemistry, they air gulp naturally to exercise their lungs and sometimes get a little over excited..
 
Is there not a danger of messing up your water hardness and therefore PH by adding RO water with no buffering? Over time there is maybe potential to drop your PH buffer capacity enough that you will start getting wild PH swings
I could be wrong (it happens often) but in my head:
You have a tank with tap water around say 6KH. You top up with RO water and that maybe drops it to 5.8KH. You then do a water change with tap water and that brings you buffer back up a bit but maybe not right back to 6KH. Over time your KH drops a little bit each time you top up and then eventually gets to a point where your PH can start bouncing about.

A SW tank isn't bothered by this because it has a lot more stuff to act as a buffer but I believe (and again I could be wrong) that in a FW tank it's not quite the same.

I know in the past when breeding softwater fish I have managed to drop KH and then PH quite rapidly with just small amounts of RO so not sure I would want to put it directly into my tank.
Not an issue because very few people do an exact volume water change every time- If, for example, you generally aim for 30%, sometimes you do 33% other times 28%. Over time, the amount of change is minuscule in either direction. If it worries you do a larger % water change (or an extra one) once every few months to increase your kh….P.S. Your tap probably doesn’t have exactly the same kh (or any other value) every time you do a water change. This is one of the reasons it’s a good idea to test parameters every so often.
 
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I strongly suggest that you get a lid and use it.

Axie's are fantastic jumpers....my silly lad used to jump alot once mature and he would headbutt the lid clean off its housing. They don't just just cos of poor water chemistry, they air gulp naturally to exercise their lungs and sometimes get a little over excited..
He is only 3 inches right now, The tank is half filled, so he cannot jump out. He is going into a new, bigger tank as he grows. They Can't they jump a foot in the air can they?
 
He is only 3 inches right now, The tank is half filled, so he cannot jump out. He is going into a new, bigger tank as he grows. They Can't they jump a foot in the air can they?
My lad had a 20 gallon long and it was filled to about an inch off the rim...they swim alot more than you might think. Mine would literally swim about 40 laps every morning after he had eaten and would often seeminly rev up on the sand and shoot upwards in play and to get a lungfull of air....and would headbutt the lid almost every time when he breached the surface.

They are very playful animals, they don't know their own strength or speed. My lad was around 4 inches when I got him, he was closer to 17 inches when he died two and half years later. He was a big lad and he was extremely strong, stubborn and persistent....and would blow bubbles from both ends when playing - also made some seriously goofy faces when he headbutted the lid
 

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