DIY Breeding Tanks

  • #1
I have just completed a little project in between the others on the go to build some breeding tanks. This has been very successful and so I thought it would be helpful to share the method of construction with you all, hopefully saving you money!

The method is simple, cheap and effective. The object is to build 4 breeding tanks as a single unit, which can sit on a shelf, mount on a wall or almost anywhere you have space.

Over the next few days, I will be building another one, and will keep a record of the progress for you to see how it is done.


1 sheet of 12mm polycarbonate sheeting (3mx1m)
2 tubes of aquarium safe silicon
1 roll of masking tape
2 pieces of glass. (For this build, the measurements will be 7"x36" but can be cut to suit your own requirements)
1 100W heater (Short type, Hydor do a nice one just the right size for this build)
1 Small powerhead filter (Fluval 1 would do, so long as you can connect a pipe to the outlet)
1 pack of Fluval 2+ filter media
1 length of 2" electrical surface trunking
2' length of pipe to fit the outlet on the powerhead. (I used the tubing from my gravel vacuum!)

With a lot of the above materials, you will have enough to make several of these units, so keep them handy!

Step 1:
Decide on the measurements. For this build, I will make the unit 18" high x 6" deep x 36" long. this size fits very well onto wall shelving and will hold 4 x 2 imperial gallons.

Step 2:
Mark and cut the polycarbonate sheeting to the sizes. When cutting the sheet, cut through the center of the ribbing over the size you require and then trim back to the rib on both edges. (See drawing 1A,B,C & D) Be very careful not to break through the ribbing. It is a bit of a tricky thing to do, but once you get the hang of it, it's easy. (I used a small angle grinder with a steel cutting blade to trim mine back, but a sharp craft knife and glass-paper will do the job just as well)
For this build,
the back panel will be cut at 18 x 36, ribbing running horizontally
two side panels at 18 x 5 1/2, ribbing running vertically
bottom will be cut at 6 x 36, ribbing running horizontally
upper-bottom at 5 1/2 x 35, ribbing running horizontally
center divider is cut in two parts, one at 11 x 5 1/2 and the other at 6 1/2 x 5 1/2. ribbing running vertically.

Step 3:

Fill the ends of the ribbing on the upper bottom panel at both ends and smooth off.
Now things get a little more difficult! Use a drill to make holes in the polycarb as follows:

Drill a row of 10mm (7/16th) holes through the one skin only, in one of the end panels 1 1/2" from the bottom edge and another at 16 1/2" (Drawing 2 & 3) and fill both ends of the ribbing with silicon and smooth off. (don't block up the drilled holes though!) These holes will be the channel for the water flow from tank 2 to tank 3.

Drill a 20mm (11/16th") hole 10" from the bottom of the other side panel through both skins, and another hole the same size as the tubing from the powerhead 17" from the bottom. (Drawing 4) Again, fill all the ribbing with silicon and smooth off. In this instance, seal the broken ribbing inside the large holes with silicon. This will take the pipe from the powerhead in tank 4 to tank 1 and let the power cord out.

The two center dividers need to have a row of holes drilled at the bottom on one side and the top on the other side as drawing 5, 1 1/2" from the bottom and 5 1/2" from the bottom. This allows water flow from one tank to the next. As above, seal top and bottom with silicon and smooth off.

Step 4:
Once everything has been cleaned, de-burred and drilled, you are ready to start assembly. If you have never used silicon before, practice on some offcuts until you can get a nice even bead running along the edge of the polycarb. The nozzle can be trimmed to suit yourself, the smaller the nozzle the finer the bead you get. I would recommend that you have a nozzle of about 3/8th inch trimmed at a 45 degree angle for best results.

Start by arranging the pieces in order and pre-cut the masking tape into roughly 4" strips. You will need quite a lot of strips, so make about a dozen to start with.
You need to decide which side you want the pump now. All the water flow will depend on whether the pump is on the left or right. I instictively install my pump on the left, but you might want to have it on the right.

Print out Image 2

Take piece 4 and stick some tape strips under the back edge, leaving about 2 1/2" free. Take piece 1 and run a silicon bead along the bottom edge. Place the bead firmly onto the back edge of 4 and run the tape up over the join onto the back panel. (This will be very unstable and an extra pair of hands may be useful to hold this join while you get the next piece ready.)
take piece 2 and bead the back and bottom edges with silicon. Stick a few more strips of tape onto the underside of the bottom on the LHS and also on the LHS of the back panel. Carefully place 2 onto the bottom LH edge, tape and then bring the back panel onto the bead and tape there too. Press firmly on all joints, squeezing the silicon out of the sides of the joint. You now have the start of the unit!

Don't hurry this, take your time to get it right, it will save problems later. Adjust the joints to align the edges flush on the outside and press firmly into position. You should have the LHS and Back sitting on top of the bottom panel, and, if you got the sizes right, the front edge should be flush too.

Ok, so far, so good. The silicon will stay workable for around ten minutes, so once the joints are right, you can use the back of a spoon handle dipped into soapy water, or your finger to smooth the inside into a curve across the joint. If there isn't enough silicon squeezing out of the joint, run another bead down the inside of the joint to ensure an even curve all the way along. when it's done, it should look like 6!

Be very careful now, as these joints are still unstable and will slip out of line if you're not careful. Now take 3and bead the bottom and back edges as you did with 2. More tape and sit it on the RHS of 4. You now have three sides and a bottom. Line up the edges and bead it in as previous. You may find it easier to lay the assembly onto the back panel now.

Now mark the center of the back panel with a pencil or felt pen. this is where the bottom center divider, (6), goes. Check that the flow direction is correct, with the top row of holes on the opposite side to the pump. Bead the back and bottom edges and place on the center line, pressing it firmly against the bottom and back panel. This cannot be taped into place, so you may have to re-position several times before it's right.

Take piece 8, the glass front panel. bead all the edges of the polycarb, bottom, sides 7" up, center divider. carefully align the glass panel onto the beads and tape in place on all sides. smooth the inside round now, as you won't be able to get to it easily later.

Step 5:

Leave the assembly to dry for an hour or so, or until the silicon has skinned over. This will help to stabilize the assembly for the next phase. Take the electrical trunking and cut a piece long enough to fit between the front and back panels. (Should be about 5 1/2 "). Remove the top cover and trim off one leg, leaving an L shape. Silicon this in place level with the bottom of the top row of holes, leg facing upwards. This is a bit fiddly, but it works. The bottom two tanks are now complete!

Step 6:

Measure 7" from the top and mark on both ends. This will mark the top tank base. (Assuming the measurements and cuts are right, it should sit straight onto the bottom center divider.)
Bead the back and both ends of 5. Also run a bead along the top of the center divider. Again, a second pair of hands is useful here. Ease the side panels outwards slightly and slide 5into place. The polycarb should give enough to do this without breaking the seals if you are gentle. Release the sides and press firmly against 5. press 5 firmly against the back panel. As long as the silicon hasn't gone off too much, the panel should push into the rounded beads on both sides. If it doesn't, just trim them with a knife where the panel fits in, so that they don't stop it sitting tight to the back. (Difficult to explain, I know, but I hope you can understand what I'm getting at.)

Bead and fit the center divider, (7) again making sure that the flow runs the right way, (top holes same side as the pump). Press firmly into place and bead the inside of all joints.

Now you can fit the other glass front, (9), by beading all the edges and carefully positioning and taping in place. All things being correct, the top should line up all round. If the glass is slightly below the top, you can adjust it by sliding it up a little to line up flush with the top of the polycarb.

Allow the silicon to skin over before fitting the other two trays to the top tanks. Seal these in place and leave overnight to allow the silicon to fully cure.

You're Done!

Fit the pump in the bottom tank, feed the pipe through the holes to the top tank, feed the mains lead through and re-fit the plug, and test it! If you made a good job of the silicon, you shouldn't have any problems! Good luck!

I will add some pictures of the build as it progresses so you can see how it is done, but the drawings should help a lot.
  • #2
Thanks Tim! Great job on the build and on the instructions!
  • #3
Thanks Tim! Great job on the build and on the instructions!
my thoughts exactly! keep up the good work! i'm so jealous of your tanks!!!!! tan
  • Thread Starter
  • #4
I shall have to make you really green and invite you over for a weekend!
  • #5
I shall have to make you really green and invite you over for a weekend!

if not for the pond between us, we'd be there.. please have towels for the drooling.
  • #6
I shall have to make you really green and invite you over for a weekend!

if not for the pond between us, we'd be there.. please have towels for the drooling.
lol!!! you should sell tickets on the door!! tan
  • Thread Starter
  • #7
The saying is:

"The proof of the pudding is in the eating"

The new tanks are now supporting platty fry and angel eggs! The molly is just about to give birth and the guppy is heading the same way. One of our leopard danios is very heavy and will be laying very soon, another angel pair is getting ready to lay, and I now need to design a bigger group of tanks and fit them in our bathroom!

I guess you could say that the new tank system works!
  • #8
great to hear. sounds like an occasion for new vids soon? i'm glad the fish let you live with them. : lol.. this from someone with 10 tanks in their bedroom. ;D
  • Thread Starter
  • #9
just for your information, this is our bedroom as well! (Only a one bedroomed flat and our 7 year old daughter has that!)
  • Thread Starter
  • #10
Well, the angel eggs didn't hatch, but the second pair have now laid and a new batch of eggs is being looked after by the parents this time. I put them into the 2' QT to lay and they managed to lay the eggs on the ceramic floor tile that I put in there for them. I have left the parents to tend the eggs to see if that works better than moving the eggs. (Had no choice before, they laid them at the top of the water column!)

The molly finally gave birth yesterday, quite by surprize, we had given up on her doing anything and put her back into the livebearers tank! I had immense fun trying to net over 70 fry today and get them into the breeder before the male got to them!

the first batch of mollies are just about ready to be moved to the LFS now, which will help to clear a tank for the next run of swordtails, which is likely within the next 2 weeks. (providing she follows the calendar, unlike the molly!)

the breeders are arranged like this at the moment:
Tank 1: Molly fry, almost ready to move
tank 2: Guppy female, heavily pregnant
tank 3: Molly fry, new batch
tank 4: Neon male/female, ready to lay.

The second breeder tank unit has been delayed due to work commitments, but should be constructed during the next week, hopefully in time for the angel fry to be moved into before the first pair lay again! The third breeder unit is designed and will be built as soon as the second is running. This will be a 12 tank, 4 level unit, much larger than the first two and setup in the bathroom, since I really have no more room in the living room for any more! Success has it's problems!
  • #11
Incredible job using the space that you have!
  • #12
So awesome, I have three tanks in three rooms, soon to be 4 in 4.
  • Thread Starter
  • #13
here's the latest update on the breeder tanks:

Tank 1: 70 swordtail fry
tank 2: 60 guppy fry
Tank 3: betta bubblenesting
tank 4: EMPTY (Need to keep one clear to allow for water changes) Neon returned to main tank after refusing to lay!

The molly fry have been moved to a growing tank and will be ready for the LFS in approximately 4 weeks.

We also have Jack, the Dwarf Gourami bubblenesting in the top of the water column! (Not sure how this will work out, but could be interesting.)

This week I will be starting the new batch of tanks. A group of 12 in format of 3 wide, 4 high, same single filter, single heater system, each holding 2 gallons and a batch of 4 tall breeders for angels etc, in format of 2 x 2, single filter, single heater, each one holding around 4 gallons.

The other 2' tank has been installed under the new 8' and this has been divided into two to allow for more breeding pairs or fry growing tanks. This tank will be individually heated and filtered each side.
  • #14
fry city there -- do you ever get to sleep or do you also have a vampire betta?
  • Thread Starter
  • #15
have to be around at midnight to read your replies!

If you like this design but have problems locating the materials I use, check out the link .

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