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  Topic Review (Newest First)
11-30-2006 02:15 PM
auto Dry fert dispensing solution is here!

I've notice a lot of auto-dosing threads popping up lately, and while there are several liquid dosing solutions, there's mostly imaginary approaches for the automatic dry dosing of Greg Watson's powders.

I would like to propose DRY daily dosing solutions requiring various levels of preparation and automation, while only costing $25-$175. I hope we can use this thread to refute, refine, or add to the solution using available equipment products, not untested DIY fantasies.

Baggie approach;

Buy 14 3"x4" 250micron bags, and cheap airline suction cups. put each bag open side up huddled together in a short Tupperware container and spoon your daily ferts into each bag. close each bag and tie the string around the stem of an airline suction cup. maybe keep the container full of premeasured fert powder bags near your tank. place a bag suction cupped to your glass preferably near water flow, and take any previous bag out and place it into a separate container to dry out. use a bag every day, then every 2 weeks prepare your now dry empty bags with new powders. if after a few months the bags get dirt or algae, simply bleach dip them and rinse with dechlor.


Hopper Feeders

buy the largest fish food feeder with divided food hoppers used to control portion mixtures, I use this $30 feeder only as an example; hopefully we can find a larger one, but even this should be enough for the total daily teaspoon of mixed ferts most under 60gal tanks need. I'd use a 1/8-1/4 teaspoon to accurately get your powders into each hopper partition. like the baggie idea, every 2 weeks you spoon in your daily ferts into each days hopper. set it over your tank as you would to dispense food, but directly under the spill aperture, attach one of those 3"x4" (or larger to allow for spill distance error) 250micron baggies while it's open mouthed and mostly submerged in your tank water. every day the dry ferts will drop down through the open baggie, then the powders will slowly dissolve into the waterflow.

to take this idea one step further; should we find a feeder with large enough hoppers, you could dispense BOTH your ferts and pellet food in the same or alternating partitions, and simply not use any mesh baggie to catch them, just as long as they dropped into good water flow.

Note: under humid circumstances powders may cake up in the hoppers before they get dispensed. many food feeders (including this Fish Mate F14) have a air intake so an air pump can blow dry air into the dispenser keeping it's contents dry. if you can find not only a larger partitioned hopper feeder, but one that also incorporates this dry air intake feature, that would be something many here would be glad to try. - I know I would

Here is an 8 compartment cat feeder that could be mounted upside down to let the powders and food pellets spill down when the aperture disk turns to open it, however this is too large just to dispense a teaspoon or two of powders and food pellets, but you get the jist of what I'm looking for...

Here's something from Europe - more (27) larger compartments, I'm just not sure those partition trays will hold and dispense powder as they tip down when being dispense through the aperture, but it says it can dispenses dry medication, so who knows. This is a A/C powered device, so it's 24 hours timer could be extended by plugging it into another A/C timer if you want to dose every 2 or 3 days, instead of daily.
Hmm, it's expensive but this item looks very promising. I just worry all those open vents may expose the contents to too much humidity unless you rigged a fan or airhose to blow warm dry air on it. This item comes with a square funnel to make it easier to fill each tray. It occurred to me if you somehow mounted this item centrally and higher near your hot dry lighting, it would keep the powders dry and allow the dropped powder to disperse over a larger area, possibly aiding in it's absorption by your tank water.
Volume of each food tray: 3.5 cubic centimeter
1 teaspoon = 4.93 cubic centimeter.

I found this on a newsgroup:
Date: Fri, 29 Nov 2002 11:12:46 -0600
Daphne: "Does anyone use the Rondomatic or Lifeguard auto-feeders for dry
chemicals? If so, how much do the hoppers hold? The Lifeguard seems like it
should hold more per hopper since there are only 14 hoppers. Apparently
though, the Rondomatic hoppers (there are 28) are significantly larger. How
bad are they in terms of clogging up?"

I use the Rondomatic to dispense dry chemicals. Each hopper will safely hold
about 3/8 teaspoon. I say 'safely' because I've found that you have to be
somewhat meticulous about not spilling anything outside the hoppers. If you
do, the mechanism has a tendency to jam at the set point. Not a big deal if
you notice it, because you can spin the mechanism by hand and clear it up.
Mine has been in use several months now and is due for a good cleaning. I'll
try a can of compressed air on it.
The chemicals in the hopper will sometimes react with the air humidity and
form a solid crust that sometimes prevents it from dumping out. Stirring it
with a toothpick cures it. It's not as maintenance-free as I had expected,
but it's still better than dosing by hand each day. I have it set to dose
once a day. You can add more set points and dose several times a day if you
wish, which has the effect of increasing the volume you can dose each day.
But that also means that the number of days between refills is reduced
At present, I only dose a trace element powder and K2SO4 powder out of it.
Dosing NO3 out of it is dicey because once the hoppers are filled, you're
stuck with it unless you want to dump them and start over. I'm having better
results with NO3 by just feeding the fish anyway, but each tank will vary.
The amount of any PO4 bearing chemical that will be needed is so small that
it can be dosed by hand, probably weekly since it is so durable. -TW

Thanks Tom!
I wanted it to dose Seachem Equilibrium. It takes SO much water to dissolve
it that it would be easier to just dose it dry. With the 3/8 tsp/hopper, I
could get one months supply per loading. I dose 2 1/2 tsp once a week.
Never thought of compressed air for cleaning, what a great idea!
Thanks so much for the help! -Daphne

anyone with $1,200 per powder to be dosed, can get this item;

Maybe a DIY'er can steal this concept for a dry fert dispenser.

Mill Grinders

mount over your tank or sump a bank of common pepper mill grinders,
filling each of them with fert powder (a window showing fill capacity),
then slowly spin their grind handle to sprinkle ferts into your tank.
you could get cheap battery clock mechanism to turn the handle
one full rotation every 12 hours, or electric if you need more torque

what's great about a grinder based solution is even if the powders
get caked up from humidity, the grinder will granulize it again.

it turns out there already are lots of electric pepper grinders,
so this solution could be to electronically turn them on for
the duration needed to dispense the proper amount of powder.
keep in mind there are dozens of electric pepper and
finer grain SALT mills, so there may be a bit of trail
and error to find one that works best with powders.

this particular model runs on 12 volts, you could leave stuck on,
but power it with any 12 volt DC transformer for an alarm system.
put the transformer on a electronic timer we find that lets you turn
things on and off by seconds and minutes of duration. then
experiment with how many second the grinder needs to spin
to reliably dispense the desired amount of powder.

for a timer, we could use a cheap x10 based system where each
node would power up the transformer to the pepper grinders,
while all being controlled to the second by a console or a PC!
It seems the PC based controllers are Programmed by a PC
but run independantly, so you can set them to second

OK, X10 says their stand alone timer can support 4 modules
and will turn an item on and off to the second, even though
the display normally shows minutes and hours. So if you wanted
to dose more than 4 items, you would have to go to the PC
based controller, that does not require the PC to run, just to
be initially programmed.


Smarthome has more electronic timers

so let's figure out the cost of this adventure;
$50 4 electric 12v pepper mills
$60 4 electric 110v moduals & timer/controller
$30 4 12volt A/C transformers
$40 wiring & mounting misc.

now all we have to do is figure out how many seconds
does the pepper mill grinder turn to dispense the desired
amount of each fert, and set the timer accordingly
if we find that 2 ferts dose at about the same rate, we
could wire 2 pepper grinders in series to the same 12v
transformer, thus dispensing a 5th fert and beyond.
if we find that certain ferts can be combined and fairly
distributed in the same grinder, you could expand the
number of ferts being dispensed that way as well,
as long as you increase the grinding time for that mill.
I'm sure Greg with his PMDD mix experience already
knows which individual ferts evenly combine the best.

because this entire system is electric, the only part
you would see were the 4 or more 7"x2" pepper mills,
while all the rest could be hidden in your tank cabinet.
mounting would have to be on some sort of bracket
that keeps the pepper mills too far from the lights to
melt, and too far from the water to get much humidity.
as the pepper mills are attractive, and you need to
see the window to notice being low on ferts, having
this contraption displayed may not be too bad as long
as your tank is not small.

another argument for using this only for larger tanks
would be the margin for error. say we discover ferts
dispense differently over time as the powders could
potentially cake up in the grinder; a larger tank can
forgive this margin for error, while a smaller tank may not.

So the big question is;
would someone be willing to spend up to $200 on a Dry system
such as this, if he only had to refill it once every few Months,
and set and forget the controller only upon initial installation.

If you are, let me know and perhaps I'll build one for you

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