Nice ideas! I think I'm going to try the aqualifter one. I'll calibrate it using a graduated cylinder and a stopwatch and go from there. How slow can I get the aqua lifter to pump with one of those valves? I am thinking if I could get it where I could dose 4 times a day for 15 minutes each I could get it to drip the amount I need in an hour and it would work perfect. I'm just concerned I wouldn't be able to throttle back the aqualifter that much without causing harm to the pump. Since my tank is has mostly mini colonies atm I get most of what I need from kalk saturated ATO, but still need to dose 20mL of part a and b a day so I would want to dose 20mL in an hour time.
That is just an inline air valve. I like these ones, they are a little more precise
Micro Air Valve - Barb x Barb - 6 pk | ThatPetPlace.com
The aqualifter is only $15 and you can replace the diaphragm in it if it goes bad so I wouldn't worry about harming the pump. The diaphragm is only 3 bucks.
Replacement Diaphragm for Aqua Lifter Pump - 2 pk | ThatPetPlace.com
Aqua Lifter
As Impur says, no worries about harming the Aqua Lifter. Up-front cost on them is low. Repair cost is even lower. Plus, I've run them for several days against 100% back-pressure and they just don't seem to be phased by wear like that. (It's a re-dressed air pump, after all....works nothing like a conventional water pump.)
Airline Valves
I actually went out of my way to acquire those specific micro-ball valves that you link to, but after using them I switched to the cheaper, easier to find Top Fins due to their design.
I also happen to like the 90º angle you get with this valve.
The Top Fin ones are adjusted more like a gate valve with multiple layers of threads, which makes their range of adjustment pretty darned fine. On the flip side, just like full-sized ball valves, those micro valves you linked are quite stiff and therefor hard to make fine adjustments to when you're trying to dial in your dose.
If you really want to go top-of-the line, the only way to go is a Flow-Rite needle-pinch valve. 100% designed for flow-control on soft tubing, not prone to clogging since it doesn't actually handle the flow, and also has the adjustment action of a gate valve.
Needle Pinch Valve | Flow-Rite
The PV-2 is the correct model for airline tubing. USPlastic seems to have the
most reasonable pricing.
Dosing
When you're locked to a 15-minute dosing time it's very possible you may be better off diluting your two part by 50% with RO/DI water - then you can double your dosing volume and fit the doser's limitations (15 minute doses) a little easier. Also, since you'll be dripping very small amounts (20 mL equivalent) very slowly (over 15 minutes) I wouldn't worry much about breaking up the dose into multiple 15-minute doses - won't hurt, but it's unnecessarily complicated for just starting out. When you have to dose a 1000 mL per day you may want to begin worrying about this. Keep i t simple!
