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post #1 of (permalink) Old 06-02-2006, 08:18 PM Thread Starter
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Lightbulb Autodosing for Dummies

For planted tanks, especially those high-lit ones, a good regular supply of nutrients is one important part of success. Instead of daily mixing and applying, let's do some autodosing so you can enjoy your tank, and don't have to worry while on vacations either.

There are many ways to set up autodosing. I have described this method previously, but since it works so well and the original threads have been diluted by other discussions I thought I do a little step-by-step how-to write-up.

1) Materials we need (approx cost):

Water pump ($15)
Container ($1)
Tubing ($2)
Electronic Timer ($10)

2) Setup

Connect tubing to pump outlet. Having some scrap tubing pieces in different diameters sometimes helps to bridge pump outlet to tubing, or cut one of these. We need regular airline tubing, long enough to reach from the pump to the rim of the aquarium. Add some sort of nozzle to the end of the tubing. I use the little connectors for mini airline tubing, sold at pet stores (see second photo). This will roughly determine the amount of solution dosed each time.

Cut a slit and a hole into the plastic container so the power cable from the pump and the tubing can go out of the container while the lid is closed. To avoid cracking the plastic I use a heated knife to carve out the hole.

3) Adjust dispensed amount of solution

A) Decide dosing and refill frequency. For examply, I dose daily, and refill every two weeks. So I need to get 14 dosings out of the container.
B) The little nozzle on the end of the tubing (which goes into the tank) determines roughly how much liquid is dispensed each time.
Other factors that you can play with:
- power of pump (watts or gal/hour) - I use mostly 6W pumps that do ~160g/h
- position of setup relative to tank level - place it on the same level as tank, or below in stand
C) Fill the container with water, place it where it should go, put the tubing over the tank rim or into a container at exactly the same height as the tank, and do some 1-minute runs. With a marker, mark the respective levels of solution (water) which will later tell you how full you fill the container to have enough solution for (in my case) 14 dosings, and then every day be surprised how exact the doser doses!

4) Mix solution

Based on your current dosing, calculate how much fertilizer needs to go into the container. Say you are dosing 1/2 teaspoon of KNO3 every other day, that would be 3.5 teaspoons to cover two weeks. Decide if you want to dose macros and micros with two containers and pumps, or if you dose everything but phosphates together and do phosphates separately as needed.
For ex, for dosing my 100 gal lowish light tank, I mix
3 tsp KNO3
2 tsp K2SO4
1 tsp MgSO4
12 ml Flourish
12 ml Flourish Iron
which doses the tank for two weeks. Of course, every tank is different!

5) Program timer

You need an electronic timer that can switch one-minute intervals. I program mine to dose every day at 2pm for one minute. Why? Well, why not?

6) Gotchas

A) Siphon - make sure the end of the hosing is not submerged in tank water! Unless you use a really big container...
B) Level in container - might affect the amount of dosing, especially if the pump is too weak. Get a stronger pump...
C) Degrading solution - in my case, the micro solution starts growing stuff, and the macro solution starts smelling. For combined macro and micro dosing, after a couple of days the solution both grows stuff and smells. Not really a big issue, just keep the solution for 2 weeks max and clean container well before refilling. And the tubing and nozzle needs to be cleaned/replaced once in a while.

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