This is how I see things based on my own system:Important:
1 Bottom drains – 110mm
3 If pond / filter system is above ground a settlement chamber will work great and easy to drain by gravity. If pond is below ground it might be easier to have some sort of catchment area about ground for easy cleaning without bending down to much.
4 Good filter system and some available space to upgrade system in future for that 1 or 2 ‘extra-beautiful-Koi- I want-for-my-collection’. We all tend to over stock so make sure your system can handle it in future when fish grows big.
5 Use the biggest pipes possible with the least bends possible and try not to pump water to high. Eskom is expensive, so try to get the most out of your pump with as little losses as possible.
6 If you build a formal pond it will be wise to build a part of it above ground and then use a gravity fed system. Looks nice to be close to your fish and you can get away by saving electricity by using a lower wattage pump to perform the same job.
7 Net to catch fish and a bowl. Blue one if you intend to take pictures
8 Make your pond as deep as possible. This does not take up any more space and is handy when you have limited space
9 Waterfall return and some underwater return systemLess Important but handy
1 In a new pond a test kit will be essential although you won’t use it as much in later years. Remember the solvents will expire in the future.
2 Keep some medicine on hand, some spare parts for that ‘o-my hell- my pipes-are-leaking- days’. This normally happens when you least expect it.
3 UV light – Handy in beginning and important when pond is in full sun.
4 Temp meter.
5 Shading over pond.
6 Some sort of light around pond and at filter system if you need to do work in the dark.
7 QT pond – This is essential but not all people use this. Even a small portable one will do and can be used for hospital pond and be packed away later.
8 Drag net – Easier to catch fish with less stress chasing them around pond.
9 Microscope – If you don’t have one at least know someone with one that can use it.
10 Feeding ring so prevent food ending up in skimmer – or some sort of system in place to keep food away from filter system.If you have the time and money:
Skimmer, Power back up, independent DB for electricity, Auto feeder, Handbooks about Koi for the more serious keeper, List of telephone numbers of Vets, medicine suppliers, hardware stores and Koi shops. Lights around pond for viewing by night. Some sort of viewing area like a bridge for example. Heating system for QT in winter when used as hospital.Auto water fill up. Electronic meter system to measure parameters. Logbook of pondLast but not least – A fridge near your pond filled with beers for those hot summer days when you enjoy spending time next to your pond