Not a bad article but it implies the force on the glass is proportional to the weight of the water in the tank. This is not directly true as it's not the weight of the water that effects the force on the glass but the water level.
It is possible to make a 10L tank that needs 25mm glass. Alternatively the same 10L could be safely held in a tank made from 3mm glass. It all depends on the shape of the tank.
Bracing will help to some degree as stated, but the thickness of the glass still has to be able to withstand the pressure of the unsupported area. The maths (which is really what the term engineering should refer to in this case) still needs to be done to calculate the correct glass thickness. All the bracing is just the support mechanism. The advice on the bracing size seems fairly sound, maybe a little on the light side.
The bottom thickness statement is only true if the base is truly level and does not deform at all under the weight of the tank. If it does, then the glass has to be thick enough to support either the full weight or the partial load. This needs to be calculated too.