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Pond-style Tanks & Window Lighting

shangman

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13 Jul 2020
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241
Location
London
Hi All,

I had an idea for a tank by some windows and wondered about what experience people have with them and if they're a good/bad idea, since I've read arguments for both around the internet and am not completely sure.

A month ago I got myself a bargain tank with the dimensions of 100cm x 40cm (depth) x 30cm (height), and decided that it'd make the perfect BigTom-style pond tank (half the depth, but I don't have the space for any deeper), with basically no plants in the water (ideally blackwater even), and with lots of riparium growth from echinodorus, stem plants, maybe a rare houseplant or two, and providing great extra filtration.

There are two options for tank placement, the first is just in a back room with no window or anything so not difficult to plan, the second (and my prefered) option is in my living room right in front of two big south-facing windows. I've attached a photo of the spot, the side table is approx 2m long, the tank would sit in the middle with plants either side. My current thought was that the only tank light I would add is a spotlight (maybe AI Prime kinda thing), mounted in the slot between the windows so we can see the fish. The tank will have some sort of painted/stuck on background behind it to stop sunlight getting in that way/hide the windowframes. I would be taking out the sidetable and making sure to reinforce it well, just in case, and adding a new top instead of the fabric that's waterproof, strong, and looks nice.

Here's a photo: the scale is weird, everything looks smaller than it is - the table is 2.1m long (the plants are massive too, some are moving to other parts of the house).

PXL_20210405_142528449.jpg


Because the tank would be a blackwater style, I'm not too fussed about a bit of algae, but also I don't want it to be FILLED with algae, and I'm not sure about what the riparium plant growth will be like year-round. My gut says it would be fabulous, but I wanted to check first... I have no experience with tanks and windows, and I wondered if anyone here does I'd love to know the benefits/pitfalls of doing it this way.
 

Nick potts

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25 Sep 2014
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556
Location
Torbay
Hi shangman

I've tried 2 tanks on south-facing windows now. The first one i tried to keep the water crystal clear, lots of emersed growth with peace lilies and ferns etc, looked great for a while but eventually with the bright sunlight algae started to really bloom, and required cleaning every few days.

The second I decided to use lots of monapi wood, this resulted in very dark water, this has been running around 7 weeks now, and so far algae has been minimal, I do 100% water changes every week, which is practical as it's right next to the kitchen sink and only 20L which may help, but I believe the dark tannin-stained water is the biggest reason, the same also plays out in a shrimp tank with lots of botanicals I have right next to my high tech setup, which I can also leave for months without much in the way of algae build up on the glass etc.
 

mort

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15 Nov 2015
Messages
1,530
My tank is in a similar position but I have it slightly to one side of the window so it doesn't get constant direct sunlight until the afternoon (so ten hours or so in the summer). Tbh I wouldn't have a tank now that didn't have natural sun beaming into it because the fish look so much better and they really love it to.

I'm short of time at the moment but I think your plan is feasible and fun. This very old blog is what got me started Biotope in my study, a low-tech natural aquarium - tuncalik.com - Natural Aquariums and Sustainable Life and it's worth a glance.
 

shangman

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13 Jul 2020
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Hi shangman

I've tried 2 tanks on south-facing windows now. The first one i tried to keep the water crystal clear, lots of emersed growth with peace lilies and ferns etc, looked great for a while but eventually with the bright sunlight algae started to really bloom, and required cleaning every few days.

The second I decided to use lots of monapi wood, this resulted in very dark water, this has been running around 7 weeks now, and so far algae has been minimal, I do 100% water changes every week, which is practical as it's right next to the kitchen sink and only 20L which may help, but I believe the dark tannin-stained water is the biggest reason, the same also plays out in a shrimp tank with lots of botanicals I have right next to my high tech setup, which I can also leave for months without much in the way of algae build up on the glass etc.
Aha, this is very interesting, especially the differences between clear & blackwater. What was the type of algae in the clear-water tank that overtook it? I feel like some types of algae could work nicely in this kind of tank, though I'm imagining with clear water it's some sort of evil long 'pull it out in clumps' type.

Awesome to know that your new blackwater tank is working well so far, I'd love to see pictures of them if you have any :) 100% waterchanges probably do help a lot, I'm hoping to get away with less than that (except maybe the first week), as it's going to be 100% rainwater.

My tank is in a similar position but I have it slightly to one side of the window so it doesn't get constant direct sunlight until the afternoon (so ten hours or so in the summer). Tbh I wouldn't have a tank now that didn't have natural sun beaming into it because the fish look so much better and they really love it to.

I'm short of time at the moment but I think your plan is feasible and fun. This very old blog is what got me started Biotope in my study, a low-tech natural aquarium - tuncalik.com - Natural Aquariums and Sustainable Life and it's worth a glance.
Ooh, very exciting that you wouldn't go back to regular lights only, looking forward to seeing how the fish look and act differently then! And very glad you think this window tank could work. Thankyou for the biotope link, that's v interesting, makes me want to keep some scarlet badis one day (maybe once some UKAPS members have bred them) :)
 

mort

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15 Nov 2015
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In my case I keep the tank as mostly clearwater but with a slight tint because I use rainwater. I had a little algae to begin with and have a touch (really minimal) of brush algae on really really old leaves but apart from that I only have had some cyano in the substrate at the back where the direct light hits. I think your plan of blocking the back of the tank out is the best idea as it means the sun hits from above and won't cause the issue I have. I'd change mine but it's through the back where the light comes and it's too high up in the window to block that area off (I've recently changes the substrate from aqua soil to sand to see if this helps but the old soil had been undisturbed for 8 years).

I do think you need a weed to help with algae. This is the tank I had the monstera in and I think in the thread I listed he had a monster cyperus (like the one that popped zozo's tank). I also keep guppy grass and lots of floating plants, so easily croppable plants is good. I've switched to a peace lily this time because it's more manageable.

The biggest factor for me with this positioning, isn't algae, it's temperature fluctuations. I have the heater on this tank set at 22c but in the summer it can hit 28c or slightly higher (I do have a lid on mine because I have jumpy pencilfish). Even with constant warm weather it never gets above that but it does play havoc with any shrimp you have Inthe tank which is why I moved them to a cooler tank.

I'm not at home at the moment but I'll try and add some more later when I am.
 

shangman

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13 Jul 2020
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Location
London
In my case I keep the tank as mostly clearwater but with a slight tint because I use rainwater. I had a little algae to begin with and have a touch (really minimal) of brush algae on really really old leaves but apart from that I only have had some cyano in the substrate at the back where the direct light hits. I think your plan of blocking the back of the tank out is the best idea as it means the sun hits from above and won't cause the issue I have. I'd change mine but it's through the back where the light comes and it's too high up in the window to block that area off (I've recently changes the substrate from aqua soil to sand to see if this helps but the old soil had been undisturbed for 8 years).

I do think you need a weed to help with algae. This is the tank I had the monstera in and I think in the thread I listed he had a monster cyperus (like the one that popped zozo's tank). I also keep guppy grass and lots of floating plants, so easily croppable plants is good. I've switched to a peace lily this time because it's more manageable.

The biggest factor for me with this positioning, isn't algae, it's temperature fluctuations. I have the heater on this tank set at 22c but in the summer it can hit 28c or slightly higher (I do have a lid on mine because I have jumpy pencilfish). Even with constant warm weather it never gets above that but it does play havoc with any shrimp you have Inthe tank which is why I moved them to a cooler tank.

I'm not at home at the moment but I'll try and add some more later when I am.
There's certainly nothing wrong with a bit of algae here! A bit of BBA I feel could actually look quite nice, I was looking in a local stream at the weekend and it's filled with what looks like super long BBA among the rocks and I rather like it there.

The riparium planting is definitely the most er... experimental part of the tank! Definitely agree that I need a good amount of plants there to soak everything up. At the moment my dad has a smaller species of monstera which he wants to add to the tank, and we're planning on using some echinodorus, lots of emergent stem plants and some sort of grasses so it looks like tropical-natural (hopefully). I think there will be a lot of growing and trying and swapping out, I wanted to start with taking the stem plants from my current tanks + my new hightech, and growing them as emergents in the pond tank to see the different forms and how they grow differently, and I'm also looking at various tropical pond plants but they all seem to grow massive very quickly. I think at the back of the tank behind wood I'll have a high bank to plant these kinds of things on, or maybe will try making some hydrophyte-esque floating rafts. Also planning for some floating plants.

TEMPERATURE... omg I hadn't thought of this at all that is such a good point. My tank last summer hit 28c too, and it didn't have any sunlight, so I can imagine it could get worse. It is a little cooler in my living room, I wonder if doing something like adding a mirror to the back of the tank to reflect extra heat would help, along with keeping the blinds down most of the time. I'm not planning on keeping any shrimp in the tank (will be all rainwater), maybe will have to check which fish would be ok with that tempturature. Did your pencilfish mind it? They're on my list of fish to keep with this one (though it won't have a lid so maybe not!?)
 

tam

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5 May 2011
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I wonder if you could use frosted window film that blocks some of the light so helps with algae issues and would also give you a better view of the fish rather than looking all the way through?
 

mort

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My pencilfish love the extra warmth judging by the amount spawning activity. I like the natural yearly temperature cycle and the way the fish react.

When we have really really hot days in the mid thirties I do lower the blinds before the direct sun reaches the tank but don't use blinds any other time. It's also easier because the tank is upstairs so I can leave the window open at night to take a little of the heat away. With cooling fans you shouldn't have much issue keeping it to 28c at the most even without any other cooling methods.
One thing I do is do a water change but keep the water, leave it outside so it cools by a few degrees overnight and then put it back in the tank. This was a method I had for getting things to breed but it can drop the temperature by a degree or two if you need be. We do live in a normally cooler climate though so these days are few and far between for most.
 

mort

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I'll just add, the mirror might work but it's really the ambient temperature that will heat the tank. All blocking the back out will do is slow this temperature increase (I don't know if blacking it out might actually increase the temp unless you left a gap between it and the glass). With mine a few days of excessive heat only raise the temp by a couple of degrees, it really needs quite a prolonged period to get it up to 28c or higher.

Polystyrene or a similar insulator would help stop the back heating up and if I was you I'd perhaps consider something removable so that in the winter or cooler months you can enjoy the low sun blasting through the back, when it's not strong enough to cause problems.
 

Maf 2500

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Great project, I am sure you can make something that works well in this space. If you have a lot of emergent plants it will stop a lot of the direct sun beating down on the tank in high summer but the back wall is of some concern.

In a south facing window there are going to be two types of heating going on during a hot summer day - ambient and radiant. You can't do nuch about the ambient unless you have air conditioning but the radiant is literally a direct line of sight thing; close the blinds if they are thick/solid or put a bit of plywood or whatever as a screen behind the tank. It doesn't need to be anything fancy like a mirror or polystyrene, just something that can block the rays of the sun.

Totally agree with mort when he says:
if I was you I'd perhaps consider something removable so that in the winter or cooler months you can enjoy the low sun blasting through the back, when it's not strong enough to cause problems.
We are talking about the UK so only likely to be an issue during a few days, or at most a few weeks, per year so having an unsightly removeable back screen should only be a very temporary inconvenience. (It doesn't even have to be unsightly.)
 

shangman

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13 Jul 2020
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241
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London
I wonder if you could use frosted window film that blocks some of the light so helps with algae issues and would also give you a better view of the fish rather than looking all the way through?
This is def an option that I'll check/try out, I want to avoid seeing the turquoise-green and red of the walls & windowframes behind, but maybe the frosting can blur that enough that it's not too obviou.. If the sun through the back is fab then will have to try it!

I'll just add, the mirror might work but it's really the ambient temperature that will heat the tank. All blocking the back out will do is slow this temperature increase (I don't know if blacking it out might actually increase the temp unless you left a gap between it and the glass). With mine a few days of excessive heat only raise the temp by a couple of degrees, it really needs quite a prolonged period to get it up to 28c or higher.

Polystyrene or a similar insulator would help stop the back heating up and if I was you I'd perhaps consider something removable so that in the winter or cooler months you can enjoy the low sun blasting through the back, when it's not strong enough to cause problems.

Yeah the mirror would just be for the sun, when the ambient temp is up.. we'll all be hot together! Just thinking back to those VERY HOT days/weeks last year that seem to be becoming more common, hopefully the fish won't suffer. That time last year I didn't have any fish yet so no experience! Polystyrene could work, I'm thinking of making a DIY backlight which would add a bit of a gap and maybe help with this issue too, and would be quite easily moveable.
My pencilfish love the extra warmth judging by the amount spawning activity. I like the natural yearly temperature cycle and the way the fish react.

When we have really really hot days in the mid thirties I do lower the blinds before the direct sun reaches the tank but don't use blinds any other time. It's also easier because the tank is upstairs so I can leave the window open at night to take a little of the heat away. With cooling fans you shouldn't have much issue keeping it to 28c at the most even without any other cooling methods.
One thing I do is do a water change but keep the water, leave it outside so it cools by a few degrees overnight and then put it back in the tank. This was a method I had for getting things to breed but it can drop the temperature by a degree or two if you need be. We do live in a normally cooler climate though so these days are few and far between for most.
I was just reading in another thread last week about how keeping tanks tep lower in the winter and higher in summer benefits them and shows off more natural behaviour, I find that so fascinating and I think will try it with this tank. I love that there are so many things to consider and experiment with to get the fish and tanks really healthy and natural. I love it every time I change something and the fish just start relaxing more and doing more natural behaviours, like adding loads of dried leaves and using playsand to get the cichlids sandsifting constantly. Temp def seems like a big thing that is v often ignored!

Thank you for the water change tip and telling me what you do to manage the sun! V good to know and be prepared for when those mega-hot-omg days return. The tank is in our front room, which luckily is already one of the most balanced rooms in the house temp-wise.

Great project, I am sure you can make something that works well in this space. If you have a lot of emergent plants it will stop a lot of the direct sun beating down on the tank in high summer but the back wall is of some concern.

In a south facing window there are going to be two types of heating going on during a hot summer day - ambient and radiant. You can't do nuch about the ambient unless you have air conditioning but the radiant is literally a direct line of sight thing; close the blinds if they are thick/solid or put a bit of plywood or whatever as a screen behind the tank. It doesn't need to be anything fancy like a mirror or polystyrene, just something that can block the rays of the sun.

Totally agree with mort when he says:

We are talking about the UK so only likely to be an issue during a few days, or at most a few weeks, per year so having an unsightly removeable back screen should only be a very temporary inconvenience. (It doesn't even have to be unsightly.)
Thanks Maf! Yes with the ambient I'm hoping that putting it in the most temp-stable room in the house (warm in winter, cool in summer) that shouldn't be too bad except for the nasty-hot days. It is true - on those days everything sucks anyway, so can easily do something cheap and ugly to keep the tank ok for then. I can never manage to do anything during those days, so just shoving down the back will probably be all I'm up to!

Thinking of making a short-depth light box for the back of the tank to highlight the blackwater (hoping to make it look nice with driftwood and toanicals) (and in case the sunlight doesn't get to the whole tank - as you said the plants can block a lot), so maybe that can work well to cover as well.
 
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