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Adventures in Dosing-Pump Fertilization
Over recent months, I've had good results by both increasing the amount of
water-column fertilizers as well as dividing the dose up into three
portions throughout the day. Given also the number of ingredients I'm
using, both commercial and chemical, I decided to try a dosing pump not
only to administer the fertilizers around the clock, but also to replace
some of the evaporate from our 135-gal by diluting the fertilizers in
distilled water. Even with multiple manual dosing, I found that, e.g., the
iron concentration can drop from 0.2 to 0.1 ppm in the course of 12 hours.
Granted this is precipitation as well as uptake, but nontheless the water
concentration falls rapidly. I assume some other metal micronutrients have
a similar fate.
I checked with Greg Morin of Seachem, who felt that the combination of
products I had in mind would not adversely interact. After two negative
experiences with other brands of pumps (the Eheim Liquidoser and then the
AquaTune dosing pump were returned as both had various defects and did not
work properly). I settled on the LiterMeter made by SpectraPure. It's a
precision pump that can deliver anything up to 100 L per day. Based on both
our tank evaporate and convenience, I chose to make up a week's supply of
my fertilizer cocktail diluted with distilled water to 3.5 L. This fits
comfortably in a gallon container that I marked off in 0.5 L increments. I
dose 0.5 L per day. Some time before the end of the 6th day I change
containers and save the remaining fraction to add at the next water change.
The LiterMeter was $240, which I admit is a luxury, but then again so is
most everything for a show tank. The unit is small and very lightweight. It
can stick to any wall or surface with the supplied Velcro mounts. You
connect it with the supplied 1/4" tubing to your water/fertilizer container
(intake) and to your tank (outlet). There are two rotary digital dials. The
first (3 digits) is to set the calibration. After you have everything in
position and your pump and outlet are at the final height, you time how
long it takes the pump, set to running continuously, to fill a 500 mL
measuring cup (usually under 2 min). A little simple math and you set the
calibration dial to the amount pumped in 1 min (which was exactly 300 mL in
my case). You dial in the amount of liquid you want to deliver in the
course of 24 hr on the other dial (4 digits going up to 99.99 L), turn on
the pump, and that's it! Once you set the calibration, you can change the
amount to deliver per 24 hrs at any time -- you just turn the pump off and
on again to change to the new volume.
The LiterMeter calculates how much to deliver each time it doses, which is
at most 150 times a day. For the curious, this works out to every 9' 36".
For very small volumes (my case) it may sometimes skip a cycle since there
is a minimum it can dispense (it saves the fractional amount not dosed in
an internal buffer which, when filled, adds the extra to the next cycle).
At my small daily volume the unit actually pumps for only about 1-2 sec.
When pumping it's fairly quit and sounds like a sewing maching trundling in
another room -- otherwise it's completely silent (a flashing green light
tells you the unit is running; a red light goes on when it doses). The unit
is very accurate -- certainly more so than the felt-tip lines I've drawn on
my gallon container. I'm certainly you can get the accuracy to within a few
mL per day, but since we all have some evaporate I see little reason to try
to dose very small quantities of undiluted liquid commercial fertilizers.
The unit comes with a cut-off switch, which you can mount in your tank.
This is designed more for reef tanks where you want to keep your tank water
height at a given level (you would set the unit for a high daily amount and
it cuts off if the tank level reaches a certain point on the in-tank
rod-switch). Since I'm using the LiterMeter to dose a precise amount of
diluted fertilizer, I don't use this limit-switch. It has a three-roller
direct-motor drive, so that the liquid you are dosing never comes in
contact with any motor parts. For that reason there is no damage if your
liquid should run out and the pump (which is self-priming BTW) runs dry.
I'm told that maintenance will be as infrequently as every 1.5-2 years,
since I'm not dosing a caustic substance. More info at
Two tumbs up from
Jared, who has no connection with the manufacturer and whose current
Seachem Excel (just started)
Karl Schoeler's Natural Gold
Boric Acid (pinch)
Shaken, not sirred.
Jared Weinberger jweinberger at knology_net
______ http://www.knology.net/~jweinberger/ ________