Kalk dosing via MaxiJet venturi: possible?

[t-dizzle]

I'm wondering whether it's possible to use the venturi connector on one of my Maxijets to draw in kalkwasser slowly via airline tubing? The tubing would would rise about 4 feet from the top-off jug under the display tank. I can insert a valve to regulate the flow rate of the kalkwasser and a check valve to guard against back-siphoning when the PH is turned off.

For those who are curious, I don't want an unsightly gravity drip reservoir above my tank and I'd rather do things simply, without adding any more pumps if possible.

If this doesn't work, does anyone know of an auto-topoff unit that can sense a water level change of 1/4" or less? Most units I've seen require a change of 1" or more, which is way too much of a swing for me. I don't have a sump.

Thanks!
T./

[manderx]

too hard to set the rate, since you won't be able to count the drops. and the check valve will be rendered worthless by the first couple day's worth of kalk that goes through it. plus it will crust up the venturi daily i'd bet.

just get a dosing pump. do a search on ebay for 'peristaltic'. i just got a pair of masterflexes for 30 bucks each. avoid the medical ones. my plan is to wire in relays so i can control them with float switches. the normal vertical float switch that everyone uses seems to be well within 1/4" from my experience.
http://www.floatswitches.net/

[shelburn61]

I agree you are asking for trouble. An aqualifter pump would work ok, but a perstaltic pump is your best bet. My modified medical dosing pump does a great job. Not sure why Manderx doesn't like em?

[crypto]

your check valve will fail. I would use a separate pump with no chance of siphon.

I use float valve to trigger a relay which pumps water through a sealed jar of kalk and then into the tank. the tube that enters the tank (in the sump) is above the water so there is no siphon when the pump turns off. i use a microjet maxi-jet pump.

besides, i don't think a powerhead will pull 4 feet via the venturi.

[manderx]

My modified medical dosing pump does a great job. Not sure why Manderx doesn't like em?

biggest reason is because they get their pinching-action from tension on the rollers while 'real' peristaltic pumps pinch the tubing between the rollers and a fixed wall. so you can use much more rigid tubing that can last for years, *especially* when dosing kalk which tears up the medical tubing and can split them if you don't change them every 2-3 weeks (they are designed to be changed daily). i used a medical way back and got the carpet wet a few times from the tubing splitting at ~3-4 weeks old, plus as the tubing streched it pumped far less, so i had to fiddle with the rate often to keep it steady. then, even though the alarms were disabled, it would still lockup and beep at me for various reasons.