# Tank Divider



## hoppycalif (Apr 7, 2005)

I'm thinking seriously about getting a 10 gallon glass tank and putting a divider in the middle to make it 2 - 5 gallon side by side tanks. To do this I would just have a piece of glass cut locally to fit inside the front to back of the tank, and silicone it in place. By doing this I could do some testing I'm interested in, with two tanks getting exactly the same amount of light, same temperature, and virtually the same water. And, if that got too boring I could keep a pair of Betta Splendens in it, without them fighting to death.

Has anyone tried dividing a tank this way? What kind of problems might it cause for me?


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## mistergreen (Mar 3, 2007)

People make dividers often for bettas but you'd want holes in the divider for flow from the filter. It might be easier to use acrylics sheet so you can cut and drill yourself.
Some just use those plastic crochet canvas. It has holes in it already.


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## hoppycalif (Apr 7, 2005)

I plan to use very small in-tank filters, two of them. At least to start out I plan to use the El Natural method, so I could try it with no filter at all. I don't want the water to flow from one side to the other. I want them to be isolated.

The only potential problems I see are the two extra surfaces to keep clean, and the very small possibility of the front and back bowing out slightly and opening a gap at the junctions. A ten gallon tank doesn't have much bowing out, so I don't think that will happen.


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## mistergreen (Mar 3, 2007)

ahh, cutting the glass will be tricky. You'd want to cut maybe 2mm smaller than actual size so you can slide it in.


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## hoppycalif (Apr 7, 2005)

Yes, and I just don't do glass cutting for that reason. But, I did find a close by glass store that advertises that they can cut to any size. I want a +/- 1/32 inch tolerance on the front to back dimension, but I haven't yet asked if they can do that. I have never been able to get glass cut to that accuracy before. And, I have no idea what it would cost.

I may just use 1/8" acrylic plastic - cheap and easy to work with. I used to have some of that siliconed to the inside of a glass tank, with no problem, so that's probably the best way to do this.


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## bertha (Sep 19, 2018)

Tagged, this seems like a very interesting thread


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## Michael (Jul 20, 2010)

OK, I'll ask the obvious question. Why not just buy two 5 gallon tanks and put them side by side under the same light?


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## hoppycalif (Apr 7, 2005)

Michael said:


> OK, I'll ask the obvious question. Why not just buy two 5 gallon tanks and put them side by side under the same light?


Too simple? No, seriously, one 10 gallon tank costs less than two 5 gallon tanks, and the 10 gallon tank shape lets me use a single light fixture instead of two light fixtures, which could be different. And, I fell in love with the idea about a year ago.

I got the tank at Petco, at $15 (dollar per gallon sale, modern version), and it only cost me $8 for the piece of acrylic to make the divider, and the hood for the tank, with incandescent light sockets, to be used with LED versions of the bulbs, was only $31. So, this meets my goal of a very cheap way to do what I want to do.


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## Michael (Jul 20, 2010)

Makes sense!


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## TAB (Feb 7, 2009)

remember you have to cut the corners off the bottom of the glass so that it does not cut into the silicone.


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## hoppycalif (Apr 7, 2005)

TAB said:


> remember you have to cut the corners off the bottom of the glass so that it does not cut into the silicone.


Is it better to trim the divider corners, or cut the sloppy silicone at the tank joint? As I understand it, it is the silicone between the end of the front/back glass and the bottom glass that seals the joints. Trimming the acrylic divider corners is certainly the easy way to do it.


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## hoppycalif (Apr 7, 2005)

This is my new 10 gallon Aqueon, Petco sales bargain tank, with an All Glass top from Amazon, in which I will use two of these bulbs: https://www.amazon.com/gp/product/B07GZLX4Z9/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 I tried the 40 watt equivalent bulbs, but only got 23 PAR light intensity, in empty tank. I want about 30-35 PAR. I should have the brighter bulbs tomorrow. The stand is one I made about 10 years ago, for a 15 gallon high tank, with the same footprint.


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## TAB (Feb 7, 2009)

hoppycalif said:


> Is it better to trim the divider corners, or cut the sloppy silicone at the tank joint? As I understand it, it is the silicone between the end of the front/back glass and the bottom glass that seals the joints. Trimming the acrylic divider corners is certainly the easy way to do it.


the divider.

if you are using acrylic for the divider, make sure you have a slight gap. acrylic expands as it absorbs water. which is ~3% by weight. if its a "pressure fit, it will crack a tank/pop a joint.

about a 1/16" gap is fine for a 10.


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## hoppycalif (Apr 7, 2005)

TAB said:


> the divider.
> 
> if you are using acrylic for the divider, make sure you have a slight gap. acrylic expands as it absorbs water. which is ~3% by weight. if its a "pressure fit, it will crack a tank/pop a joint.
> 
> about a 1/16" gap is fine for a 10.


I have been wondering about that. I knew acrylic expands from water absorption, but I didn't think it was that much. Maybe I need to look at the cost of using a glass divider instead. I can see a leak developing if I use acrylic, especially if I drain the tank and leave it dry for a few months. Thanks for the heads up!

Would a two piece divider, overlapping in the middle, prevent the expansion from pushing the tank glass front and back? I'm not sure how I would stop leakage through the overlap - much more thought needed!

EDIT: Some googleing and I found that acrylic expands around 1% over about a month and a half, but the rate of expansion has dropped much lower during that time. So a 10 inch dimension would become about 10.1 inches. That suggests that a divider between two glass panels should be about 1/8 inch shorter than the gap between the panels, or 1/16 inch all around it. That should work out fairly easily, and it lets the silicone absorb the expansion. Am I missing something?


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## hoppycalif (Apr 7, 2005)

https://www.amazon.com/gp/product/B07GZLX4Z9/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 is 60 watt equivalent, 6 watt actual LED bulbs. They are giving me 30 PAR at the bottom of the empty tank, so they are perfect! I didn't even know these bulbs existed until I started looking on Amazon for LED bulbs that would fit the hood I have. I have no idea how long they will last, but they give very nice white light, and good intensity, with 82 CRI which is pretty good too.


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## hoppycalif (Apr 7, 2005)

Acrylic divider now installed, silicone sealed, and setting up for a day. It isn't a difficult job, but strong hands help when you squeeze silicone out of a small tube! I cut the bottom corners off the divider, and put notches in at the top corners to clear the frame ledge, and allow for expansion. $20 worth of masking tape, silicone and acetone at hardware store - a place I could spend all day in.










Obvious "amateur hour" project! I may try to scrape off some of the excess silicone.


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## hoppycalif (Apr 7, 2005)

The tank is full of water now, sitting outside on the deck. If the acrylic expands and cracks the glass, which I don't think can happen, it won't dump the water on the floor. I'm thinking about keeping it filled for 24 hours, but I may make it longer. No rush, since I won't be setting it up until I move, in about 3-4 months. I did this now, because I won't have any space to do this type of work where I will be next.


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## hoppycalif (Apr 7, 2005)

In 48 hours, no leaks, no bulging anywhere, and no problems. So, I drained it, brought it back indoors, and scraped off a lot of the over spread silicone. Looks pretty good to me, for what I want. Now, to buy a pair of Hagen Elite mini filters, and I will be ready to set it up when I move in a couple or so months. First step will be to scape both halves the same, same substrate (natural soil with pool filter sand on top), same plants, etc. That will verify that I can get the same results with two independent tanks.


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## hoppycalif (Apr 7, 2005)

Now that I am in my new apartment I can begin to experiment with this divided tank. I now have both sides with the same substrate, Black Beauty potting soil, capped with SafeTSorb, about a half inch of the soil with about 3/4 inch of cap. Both sides have a Hagen Elite filter, set to minimum flow. The light fixture has the same bulb on each side. I planted an Echinororus Kleiner Prinz on each side, with about a dozen dwarf Sagittaria Subulata, and a couple of bunches of floating plants - Salvinia Minima. The two sword plants aren't quite the same size, but that shouldn't matter. Now, I have to see if I can get both sides to grow equally well, otherwise any comparison test would mean nothing. I guess that about 2 months should work for that. I will start a new thread when I get ready to actually do any testing.


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## Michael (Jul 20, 2010)

Cool!


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## hoppycalif (Apr 7, 2005)

It isn't easy to get two side-by-side tanks to follow exactly the same plant growth pattern! I had to move some of the floating plants from one side to the other, to keep them about the same. Other than that the two halves look like they are almost doing the same.

Belatedly, it has become obvious that I can't put a Beta fish in each half - they would just jump over the divider and try to kill each other. So, I will look for an alternative fish.


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## Michael (Jul 20, 2010)

Female bettas would probably be OK, or maybe paradise fish.


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## hoppycalif (Apr 7, 2005)

From what I have read, Bettas won't charge through floating plants to try to jump over the divider. I have lots of those, and I should be able to concentrate them along the divider. Does this really work???


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## ObiQuiet (Oct 9, 2009)

hoppycalif said:


> Belatedly, it has become obvious that I can't put a Beta fish in each half - they would just jump over the divider and try to kill each other. So, I will look for an alternative fish.


I once used reticulated foam as the divider between two bettas. Worked fine, as the foam extended above the waterline and was cut to a tight fit.

Edit: NVM, I realised your goal was to have independent water...


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## Michael (Jul 20, 2010)

hoppycalif said:


> From what I have read, Bettas won't charge through floating plants to try to jump over the divider. I have lots of those, and I should be able to concentrate them along the divider. Does this really work???


I think a lot would depend on the strain of betta that you select. Plakat bettas with their normal short fins would be better jumpers. But the exaggerated long/double/split fin types seem to have trouble just swimming normally, much less jumping over a divider.

Please don't hate me, betta breeders. Your fish are beautiful.


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## hoppycalif (Apr 7, 2005)

Michael said:


> I think a lot would depend on the strain of betta that you select. Plakat bettas with their normal short fins would be better jumpers. But the exaggerated long/double/split fin types seem to have trouble just swimming normally, much less jumping over a divider.
> 
> Please don't hate me, betta breeders. Your fish are beautiful.


I'm planning to get the long fin, garishly colored, sold in a cup of water, bettas. My favorite fish store has a lot of them, and, unlike what I see in PetSmart and Petco, they all look healthy. It has been many years since I have had one, so it's a new adventure for me. I agree that it doesn't look like they could jump very well, but what I read on various sites is that they are jumpers. Right now my floating plants almost cover the whole water surface, so I'm hoping that will discourage jumping across the divider.

So far I don't see any significant difference in how the plants are doing in the two compartments.


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## zahtar (Sep 29, 2019)

hello, any updates on this project?


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## hoppycalif (Apr 7, 2005)

UPDATE: This has not been a successful experiment. I am finding it very hard to get the tank halfs to do at all well. First, I had a lot of trouble getting good plants in good shape, and I let algae get a head start on the plants. When I finally got enough plants I had problems keeping both to stop re-growing algae. I am finding it much harder to keep such tiny tanks free of algae than a large aquarium is. Now, it looks like we will soon be moving again, so I am more concerned with shutting this down than in continuing to try to get them doing well.

I hate to admit this to myself, but my age is interfering too. There is so much to remember in order to succeed at this hobby, and my memory just isn't what it used to be.


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## zahtar (Sep 29, 2019)

Sorry to hear it didn't work out after all  I hope after you settle in in your new place you start something else that goes great! as for the memory you're not the only one  

Sent from my foolphone using Tapatalk


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