I know very very little about Arduino, but came across it when starting a DIY project. What I want to do is build a system for automating water changes on my salt water aquarium. Can I use Arduino to control two 12V DC peristaltic pumps in a way that I can adjust the power frequency to the pump motors in order to control the flow rate? The idea is to be able to exchange exactly the same amount of water (out with old, in with new) at a slow, constant rate 24/7 rather than doing single large water changes monthly.
I'd think it would be very much possible. I'm totally ignorant of peristaltic pumps, but if they run on DC then there is no "power frequency" involved. If they're not designed to have variable flow rates, then trying to achieve that by mucking with their power can bring no good. But what would be wrong with simply turning them on and off at whatever the desired intervals are? Do the exchange once a day, once an hour, or once a minute if you think it necessary. None of those are "continuous" but it seems to me that for this application there would be no practical difference.
Jack you're absolutely right. No need for 'continuous' exchange, every few minutes would be sufficient. All I am after is a 1.4 Gallon per day exchange, but it will be less likely to effect the livestock if done slowly over long period.
Probably a good idea to have some water level sensing too. You likely want a way to know if one of the pumps has failed before you pump the tank dry or flood it.
wildbill:
Probably a good idea to have some water level sensing too. You likely want a way to know if one of the pumps has failed before you pump the tank dry or flood it.
As your water is saline, I presume that you have to make this up in advance and store it in a tank. You'll also need to know when that tank is low, so that you can replenish it.