hi guy ..
socal ,, is that south California ..
6 k gallon is substantial qty water ..
please consider rain fall harvest and cistern
sincerely suggest you add roof top water collection to a cistern [ big as you can manage]..
i am on the Cumberland river and have plenty water , however , it costs , 20 $ / 1000 gallon . whats your price ? remember in a while the rains will stop and likely water management protocol will be enacted.
generally pond management wants 10% water change out per week . i do not do that
surely if one addressed the water harvest guys they should be able to suggest an optimal size for a cistern .. you know , area available to harvest , optimal size of cistern .
i suppose you could consider the 6k pond as retainment but i would want to bump it up ..
just my thoughts
good luck