Building my 11 000 gallon saltwater Tank - Discussion and Brainstorming


New member
Hi there,

I am in the process of building my house (in Aastria, Europe) and being an aquarium fanatic (and a little crazy according to my frinds, parents and fiancee) I need to integrate a REALLY BIG saltwater tank into the house.

The aim is to keep saltwater life and maybe a few small sharks and corals in it. I am currently a moderately successful reef tank keeper.

Before the question comes up, I'm not poor, but I'm not rich either... so the plan is to make it with a relatively low budget and low maintainanace costs.

BTW: I would be interested in some freelancer/expert willing to help with the project for an acceptable cost...

The reason I am posting this here is because I would love some critical discussions, constructive criticism and so on... and because I would have loved to find a thread like this somewhere were it not me who built it. So here it is.


Its the blue thing at the top.

The dimensions are as follows:

Area: 17m² / 180 foot²
Water depth: 2.5m / 8 foot
Water Volume: 42 000 Liters / 11 000 Gallons

The glass front:
I will have 2 viewing panes. The first one will face the living room and be of the dimensions:
18 foot wide, 7 foot high and 4 inches thick
=5.5m x 2.2m x 10cm

So basically it will be an entire wall of acrylic.


Orginally I wanted to have it twice as big, but well... costs do matter ;/

Anyways.. I went to a professional building such aquariums to ask him for a quote. The quote was (all included) €180 000 for the aquarium and equipment and so on.... which was too much for my budget.

So I realized I would have to find cheaper solutions to do this.

The curent approach will be the following:

I got a quote for the acrylic panes (there is another smaller one to the bathroom).

$21 000 for both of them including shipment from Asia to Austria. Not too bad, considering that sourcing it here from a professional would have cost me 3 times that.

By the way.. if anyone thinks, 10cm / 4inches is too thin for a water depth of 8 foot, now would be a good time to tell me! ;)

So I will have a construction company build me the tank out of concrete, with window-like openings that will fit the acrylic panes.



Building the room out of concrete is not much more expensive than building an extra room in a house... the walls are about twice as expensive, but considering that you dont need flooring, tiles and stuff, its not too expensive to get this concrete tank done.

And now this is where it starts to get a bit vague and where input from anyone would be appreciated.

From what I have read about plywood tanks, coating the concrete walls with suitable acrylic would be the way to make it suitable for keeping fish.

The first question: Can this be done DIY? Any hints, Input on what Acrylic to use and if/how the concrete would have to be treated before the acrylic is painted on? Any ideas how much acrylic is needed? Any things I am forgetting?

Ok, assuming the acrylic is on the concrete, the next step would be to put the Acrylic panes in.

The edges would be filled in with some silicone-like material. This is what I saw at a public aquarium:


The questions: Any idea what material this is? Its rubbery and quite soft to the touch. Can this be done DIY or is it tricky to do? I am still trying to figure out how to get this part done...

Well.. then the tank should be ready for water. My guess would be that I should probably flush it a few times before putting the right water in. I got an offer from a public aquarium, that I could have a truck load of saltwater from their large tanks.... so the ecosystem would set itself up faster.

The room above the tank would be essentially the same size with concrete floor, but with a hole in the center so I can jump in.

I want this to be as low maintainance as possible. I am planning to put two water tanks in the cellar that would hold 15 000 l / 4000 gallons of salt water. The plan is to have a system, where exess water simply goes into the canal, so no flooding can happen (not sure about the english term.. sorry).
I would then have a small tube of continous water flow from the tanks in the cellar into the tank. I would time it so I have a 10% water change per month. This would give me a rough no-maintainance period of 5 months, before I have to refill the tanks in the cellar with fresh saltwater.
Evaporationg water will have to be replenished with osmosis water.
Questions: Any idea how I can conbine the continous refilling with saltwater form the cellar and the evaporation-replacemnt with osmosis water? Maybe replace evaporation in the day and add the salt water from the cellar in the night?
Second question: Can I use Rainwater instead of osmosis water? I could catch it in a tank and use that as source for refilling the tank.

Now thats the expensive part. My dream would be to have crals in assorted places near the surface. The idea is to have corals on rocks near the surface on either side of the acrylic pane at a depth of up to 1 meter/3 foot. That shouldnt be too hard to manage. I think moderate lighting of the whole tank would require about 6kWh to get spots of coral growth. I am looking into combining it with a solar panel system that feeds the electricity into the tank as it is produced (No loss through batteries etc.), but still this is expensive when considering a whole month of 60 kWh per day. Without Solar panels this would probably cost me €500 / $ 600 per month in electricity. My hope was to get the monthly cost to around €300 / $350.
Maybe I will skip the corals and stick to a gloomy blue Deep sea athmosphere with less light. I will have to see.

The idea is to build metal casing that holds LED discs in the various colors, but which is cooled with circulating water. The hot water would then be used for heating purposes. this would at least reduce the heating cost of the house.

Now here some input would be appreciated. A local public aquarium told me that they usually dont need to cool (in Germany).. but 2 summers ago it was very hot and they had big problems. I calculated, that with 10 000l / 2600gallons cold tap water I could cool the thing down by 5 °C. This would cost about €40/$35 per day. The idea is to have the water run through a metal tube that is in the main tank (emergency system I would just put in when needed). As an emergency system, this would probably be better than buying a several thousand $ cooling unit. Especially if it is not needed every year.

Now talking about the filters.... I want to keep things quite simple so I can fix and modify it when needed. I would rather not have pipes go thorugh the whole house. The idea is to get 1 to 2 of these:


Each unit costs around €15 000 / $ 16 500 and is suitable for 20 000l / 6000 Gallons of sea water.
I would start with one, then upgrade if necessary. Each unit is self contained and would be placed in the room above the water.. with simply a hose to and from the aquarium.

Thats a tricky thing.... I would not want to climb into the tank 2x per week to scrape off the algae. Also an algae magnet would take ages at this size. I know an engineer who thinks he can build me an automatic scraping system that would just scrape a blade along the glass once every day. Lets see how this works... ;)

Well, thats it.

If all my plans work out, this should be an Aquarium that requires minimal maintainance:

Filling Water Tanks every 6 months
Feeding - Automated or Daily
Emergency cooling - as required every few years

Nothing else.

Now its your chance to tell me im an idiot because of getting it all wrong.... ;)



New member
For lighting you could use solar tubes, there is a build in the large reef tank subforum that uses them for lighting


New member
oh I like where your going with this...I'll be fallowing for sure. once you get the info you need should start a build thread in that sub forum.

I hope yo build a plywood tank in my custom straw bale home someday. buttt that might be years away. :(

so all I can offer is my enthusiasm!


New member
Talk to bill wann on FB. He can provided and possibly even help build some aspects(fee) for you. He has a 20k gallon in the states here
Also builds equipment