Can you get a tank that is 2 foot high instead of 3ft high?
Tanks that are more than 2 foot high are made from thicker glass, which weighs a lot more and this means you need to have a concrete floor. Tall tanks are also a pain in the butt to clean. Most people struggle to clean the front, back & sides of a 4x2x2ft tank, let alone a tank that is 3ft high.
Tanks that are 2ft high are much more practical than tanks that are 3ft high.
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I would check the stand to make sure it can take the weight of the tank. Big tanks need strong stands and if the cabinet is made of particle board and doesn't have a solid wood or steel frame, I would be careful and make sure it has a 10 year guarantee not to rot or collapse under the weight.
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How wide is the tank?
What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).