I totally agree with darky, except I'm a bit more cautious and bet 1 / 200th of my bank.
Separate bank for each system is a must. If each system is able to stand on it's own - with it's own bank - then the three must work in parallel.
The argument against one bank is simple and logical. If your systems are picking accurately they should pick the same horses a lot of the time (taking it to the extreme if they are perfect systems picking the ideal horse, albeit by different methods, then they will pick the same horse all the time).
Ergo a run of outs (presumably caused by bad luck since you have such good systems) will be three times as bad because you will be on the same losing horse three times over.

KV