DIY 3D background questions

  • #1
I'm planning to upgrade my fish to a bigger (second hand) tank once I've found a good aquarium. I would really like to do a diy 3d background with a waterfall but have never done one before so here is what I think I need to do and sone more questions:

Ok, so from what I understand you cut Styrofoam to the right size and shape it as you want, you then coat in 2-3 layers of cement, then seal it with 3-4 layers of drylok which you can colour using cement dye, then silicone it in place on aquarium, is this right?

1. Can I use concrete instead of cement?
2 Will the cement/concrete still raise PH even if coated with drylok, and if yes how long will this happen for?
3. Will cement or Styrofoam Leach any chemicals into water?
4. Do I need to leave finished design to soak in water for a bit before adding to aquarium, if yes how long for?
5. I was planning to cut out a hole in it for heater, will this melt the Styrofoam? And to ensure water can get through would I just cut a hole in it and put some kind of aquarium mesh over it?
6. Will it be possible to make a built in waterfall as well?
7. For the waterfall could I just attach the end of the external filter where the water comes out to the background so it trickles down it?
8. Can I use polystyrene instead of Styrofoam?
9.Is there any specific kind/brand of foam I need or just one that works best?

Sorry that was quite a few questions! Tbh I will probably remember some more soon that I forgot so will just add those on as I go. I'm also probably not going to start aquascaping whatever tank I get until November or maybe even December if Im really busy but just want to be prepared!

Also if anyone has any diy 3d backgrounds/waterfalls of their own please feel free to send a pic, or send any website links/videos, I could really use some inspiration! Thanks in advance!
  • #2
I wouldn't bother at all with cement/concrete. Just go straight to drylock. Then you don't have to worry about 1-4.

As long as the heater isn't too close to the Styrofoam you should be fine, you will want a large enough cavity around the heater for water flow in and out, best if you can put your intake or outtake for filter in same area.

Are you doing more of a paladarium style for the waterfall where everything sits inside the tank with a low water level or will the waterfall extend above the top of the tank?

I personally use the pink ridged insulation foam over styrofoam but both should work fine. Whichever is more easily available.
  • Thread Starter
  • #3
Thank you so much! It will be great to just skip the cement step, it will be so much easier!
I'm planning on getting a tank that is between 50-60cm tall and then only filling it up 35-40cm of the way with water. I'm then going to get some land plants and floating plants along with making the waterfall to try and make it a bit more interesting on the top half. ( I'm not sure if this is a Paludarium or not?)

Ok so slight problem, I thought I could get drylok in the UK, turns out I cannot unless I want to pay shipping fees that cost more than the actual drylok! Is there possibly anything else at all that I can use to seal it?
  • #4
I am not familiar with alternate products in the UK. Pond armor or equivalent perhaps but they are probably still more expensive than having the drylok shipped and not as easy to work with.

You could go back to the route of just doing the cement coating with color and not using a sealer. You would have to monitor pH for awhile, sometimes it can stop affecting it after a week, worse case it can be a few weeks/months. Usually a good soak and changing the water couple times a week will take care of most of it. Mix the cement with water until its basically paint like in consistency, add in your color and do a few coats. Make sure each layer is fully dry before doing the next layer or it might crack the outer layers as it sets.

Edit: for a water feature like that I think you would need an extra pump to run that. I don't know of a way to set up a filter that far above the water line to have it act as a waterfall at the same time with the return. You could potentially make a large enough cavity for the waterfall pump that if you add in some little plastic baffles and filter foam it would act as a pseudo filter for you. Have you ever watched SerpaDesign on youtube? I think some of his videos would really help with this project, great inspiration at the very least.
  • Thread Starter
  • #5
I'll have a look at alternatives for drylok but if I can't find anything I'll go with the cement (although I hope I find something else as would not like to deal with any PH issues using cement)

As for the waterfall could I not just take the end peice off of the water outlet and position the tubs so the water trickles down the waterfall diy model? I'm probably wrong though as I've never used an external filter before so have no experience with them! I've attached an image of an external filter that i've been using for referance.


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  • #6
Oh yeah, I didn't think about using a canister filter for that at all. I see no reason why that wouldn't work for a waterfall then, that's a great solution. I love canister filters, they really aren't that bad to clean and you can really customize what's inside them to your liking. They are also usually the quietest filters you can get.

You could also look into inline heaters, these are heaters that sit outside the tank and will be hooked into your return hose on the canister filter. Then you don't have to worry about it being in the tank at all. I have never used an inline heater myself so can't really say much more about them.
  • Thread Starter
  • #7
Thank you so much! I can't wait till I've found a good tank to get this started!

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