Basically, if I have two connected sparks both sat over mana pools, will this cause mana pool #2 to fill once mana pool #1 is full?
Basically like this:
I'm just trying to expand my mana storage without spamming spreaders everywhere...
No, the spreaders will just stop firing once the pool is full (and fill up with mana themselves). Sparks only interact with a select few things - most notable is probably if a spark is on a Terrestrial Agglomeration Plate, it can draw from pools with sparks - but transfers between pools will only happen if the sparks have appropriate augments. Even then some careful design may be in order.
Spark Augments also require Elven materials so are unavailable in the Botania 'early-game'.
One possible storage solution would be to store it in the form of filled Mana Tablets, although the logistics of automating those is a challenge in itself (I think there was a post on the FTB subreddit about it a few months back).
