Auto Dosing Ferts

[Purrbox]

I got to thinking today about dosing ferts while gone on vacation. There seems to be two options. You can either do a massive dose of your ferts before leaving and dial back you light, or you can set up an auto dosing system of some kind.

I've been browsing through various forum and the net trying to figure out what would be the best solution which is accurate enough and won't hurt the pocket book too badly. There seems to be four different styles for automating dosing that I've found so far.

1. IV Drip - Basically it uses gravity and a drip rate to continuously feed a small amount of fluid into the aquarium. The Kent AquaDoser is commercialized version of this method. Some have even gone as far as buying actual IV supplies and modifying them for dosing.
Example 1.1
Example 1.2

2. Waterpump on a Timer - This arrangement uses a water pump to pump the ferts into the tank with a timer set to control the dose. While effective on larger tanks, I suspect that it would have a tendancy to pump too much fluid into a Nano.
Example 2.1
Example 2.2 - Later parts of the thread apply to method #3

3. Airpump on a Timer - With this method a bit more accuracy can be achieved since less fluid is pumped into the tank. Basically the airpump is used to push the dose into the tank. There are a couple of different styles that I've seen, at least one of which appears like it would be fairly effective on a Nano.
Example 3.1
Example 3.2

4. Shringe on a Timer - The final method I've seen jury rigs a timer so that as it rotates it slowly fills and then empties a syringe over 24hrs. Check valves are used to ensure that when the shringe is being filled the fluid is drawn from the fert container and as it is depressed it flows to the tank. This method is pretty ingenious, however I just don't like the looks of the finished product.
Example 4.1
Example 4.2 - Not in English, but great pics expanding on 4.1
Example 4.3 - Also not in English, but looks really neat

I'd love to get some feedback from those of you that have actually tried one or more of the methods. Right now I'm most interested in the IV Drip, so it would be helpful to know where to obtain the necessary supplies for those of you that have used this method.

Edited to add links to examples

[hashbaz]

I don't have any experience with any of them, but the IV sounds pretty cool. Do hospitals throw these away? Are the modifications extensive?

How well would PMDD pellets work for something like this?

[Purrbox]

I finally dug up some instructions on the IV doser and have added them to my original post. Hopefully those links will help to answer your questions on this type of auto dosing.

I doubt that the pellets would work to well as they are meant to be placed in the substrate and resist disolving. You should be able to use you standard liquid or dry ferts though, which is what this is really designed to replace.

[tbonem91]

some very cool ideas!