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Discussion Starter · #1 · (Edited)
Ok so I know its been done before but I’m going to do my own version of a medium budget auto doser thread since I don’t believe any of the treads have covered things with ALL the useful details. I have kept, and will continue to keep, a journal of my finding during the process of purchasing, setting up, calibrating, and finally using the auto doser.

My tank stats
Tank: 54 gal corner bow
Lighting: 2X65 watt CF 2X18 watt T5 (non HO) Total = 166watt
Pressurized C02 controlled via Ph controller checked via drop checker

At the beginning of my planted tank obsession I used Kent Pro Plant and flourish iron. Yes I know, I didn’t have any idea what I was doing but it kinda worked.

I then got pressurized co2 and began dosing the full flourish line. Nitrogen, Phosphorus, Potassium, Flourish, and Iron. This worked well but became EXPENSIVE and I didn’t like having to pour cap full’s of ferts because it was messy and I didn’t feel it was very accurate.

I then found PFERTZ (they were having a Xmas sale) and I was able to get their whole high tech kit for less then it would have cost me to re-up my flourish line. The pumps seemed to be much cleaner and I thought more accurate.

However I realized after a few months that my potassium seemed to be putting out much less in a single squirt then all the others. I was correct. When I tested the output by squirting 10 squirts into a measuring container (should have produced close to 15ml of liquid) the output was about half of what it should have been. After testing the others I found nitrogen was drastically less then it should have been as well. After soaking the pumps in hot water the output was restored.

PFERTZ worked better for me as a fertilizer then the Flourish line; giving me faster growth and more vibrant greens. The red plants seem to loose a little color meaning the iron concentration was not quite high enough in my opinion, so eventually I started adding flourish iron as well. Dosing Pfertz was a piece of cake. Squirt, squirt, done.

Now its time to get things more precise, get the cost of ferts down to the minimum, and eliminate the need to remember to dose.

I began by researching auto-dosing methods. There are actually quite a few methods out there but most seems like buying the cheapest parachute to go skydiving to me. My thoughts were, “I want to auto dose because it will be the most accurate method of dosing possible and it will save me money in the long run.” My need for accuracy made me steer away from all methods using aqua lifters and auto feeders. I considered the consumer auto dosers but I wanted to get something that would allow me to dose for months without a need for refills.

So here is what I ended up buying (end price ($80 usd)

more specifically I bought this pump with a 3rpm motor (less rpm with larger tube means less squishing of the tube. That means longer tube life) and 3mm norprene tube (same size as airline tube so it will connect right up and clogging will be much less of a problem) and a power cord. Model number sp101.102

I chose to go without the casing because the guy from APT said I would have a number of options to mount this pump without the case. Also the case adds a bit to the price. The motor/pump is still in-cased so there is really no reason for the case other then ascetics.

The APT tech guy and I talked for a while about the difference between a 30rpm pump and a 3 rpm pump as far as accuracy and the difference was not important. The 30 rpm would have something like a .004ml margin of error where the 3rpm has a.04ml margin of error over 1 min. The margin of error can only be a negative as well.
Basically I decided this margin is so small I could rule it out as a problem.

However, in order to get a very low flow rate like I wanted I would have to use .8mm tubing on the 30rpm pump. The guy on the phone recommended not doing this if I will be creating my own solution through mixing. He said that if any kind of crystallization happened or anything didn’t fully dissolve in the mixture the tube would most likely clog and I would have to buy a new hose. Also the hose could become partially clogged and my accuracy would be totally messed up.

I think I’m totally fine with -.04ml min accuracy if it means I don’t have to worry about clogs.

Ok so now I got the pump and all looks good so lets get rid of some of the liquids I have left over.

I contact PFERTZ and asked them if it was ok to mix M, K, and N and they said yes.

Here is their email
“That is a great question, and you are correct about not being able to mix all four solutions together. The problem lies between m & p, but more specifically between iron & phosphorus. Dosing these two together into an aquarium doesn't pose problems, but at the high concentrations that would be found in your peristaltic pump, these nutrients will not play well together. For auto dosing, the minimum pumps you will need is two.”

NOW FOR SOME MATH to determine how much I need to dose each day

Daily dose of NKM PFETZ
1.2= 1 squirt PFERTZ
tank = 54 gal
pump doses .54 ml per min (this is the rated amount)

1 squirt per 20 gal daily (recommended LOW dose)
54/20= 2.7 DOSE = 2.7 squirts a day for each N , K, M
2.7 X 3 because I mix M, K, and N = 8.1 squirts total for M,K and N together

Break this down to ML so I can determine time for pump

8.1 squirts X 1.2 ml per sqirt = 9.72 ML total dose for M, K, and N solution
9.72ml/.54 ml (rated pump vol) = 18 min OMG a perfect EVEN NUMBER OF MIN!!!!

Now for the timer to turn the pump on and off. I bought

because this timer has 8 on/off cycles per day which allows me to dose little bits over the entire day. it also has 2 plugs so when i get the next pump for phos i can use the same timer to run it. . ($18 usd)

total cost = $98 for 1 pump (i had extra airline tubing so this may be an additional cost)

Trial 1

The pump did about 9.8ml in 19 min. This is with no pause. When the pump has not run in a while the solution settles back into the hose a bit and it could take a few seconds or more to get the solution back to the end of the hose. So I think I will try a 24 hr period with 8 on of cycles and measure the total output to see what I get.

9.8/19= .516ml (actual pump output) rounded

It appears complete accuracy is not possible even with a peristaltic pump unless you use a timer with programmable seconds.

Trial 2 (taking a shot at what I think it should be)

So here is my schedule
Lights come on at 11 am – 3:30 pm (4.5hr) then they turn on at 5:30 pm – 10pm (4.5hr)
Dose 1
10:46 to 10:50am (4min)
dose 2
11:48 – 11:50am (2min)
dose 3
12:48 – 12:50pm (2min)
dose 4
1:48 – 1:50pm (2min)
dose 5
4:46 to 4:50pm (4min)
dose 6
5:48 to 5:50pm (2min)
dose 7
6:48 to 6:50pm (2min)
dose 8
7:48 to 7:50pm (2min)
total = 20 min

Full day trial on the proposed schedule produced
10.8ml during one day pumped into a covered container to eliminate evaporation

10.8/20 =.54ML exactly what the rated flow rate is
to get closer to the 9.72 ml recommended LOW dose I will take 1 min off the last cycle
10.8-.54 = 10.28ml
10.28 – 9.72 = difference = .56 which is fine with me to start dosing into the tank for a period of a week then test flow again.

Trial 3

Doses worked as planned.

I trimmed a few leaves off of my assorted anubia that had brown algae spots on them. the New growth appears to be more healthy and “mature looking”

There was a noticeable increase in plant growth speed most likely due to the fact that the plants were getting what they needed in equal amounts throughout the day. Red plants seem to have improved color.

I may have to do a very large trim soon. I will wait for my root med tabs to come before I do a large trim and some replanting.

There was a noticeable increase in green algae on the tank glass near the end of the week. No algae issues involving the plants or substrate. Just more green algae on the glass that is easily wiped away with the magnetic algae cleaner. Perhaps this is normal with elevated fert levels.

I was having some issues with brown algae spots on a few plants (anubia mainly) and rocks. This problem seems to be going away. Perhaps due to growth acceleration. I don’t think brown algae has anything to do with ferts. Please correct me on this guys?

2 XP1’s
1=fine filtration and polishing (all foam)
2=course foam and biological filtration (bio stars)

The water became slightly cloudier near the end of the week. My water always seems to get a little cloudy the last day of so before water change. This time it may have been a little more then usual though. I’m going to clean out one of the filters during the water change. I cleaned the polishing filter about 3 weeks ago. This time I will clean the bio filter that has not been cleaned in a few months.

DO NOT put the end of the hose in the water or the ferts will leach out. The first day I started with the hose in the water in an attempt to avoid crystallization at the end of the tube. Upon examination of the system at the end of the day I noticed that the fert liquid was clear (inside the tube) for roughly the last foot and a half of the tube. The fert liquid is brown in the cup. This means that leaving the tube in the water allowed the ferts to leach out. After removing the end of the hose from the water the liquid in the hose was brown all the way to the end at the end of the second day.

No crystallization visible on the hose or any other parts of the setup at the end of the week.

There seems to be some kind of black particulates that settle out from the fert solution. Almost as if the iron was chelating but there is no PHOS (P2S05 or 4 in the solution so…. These particulates settle out in certain areas of the clear airline tubing going to the tank. They do not appear to travel out of the tube with the liquid.

The fert solution seems to settle back into the hose a different amount each time the pump turns off. Sometimes it does not settle back at all. I will be adding a check valve to the section of tube before the pump to see if this eliminates the settle back. On the intake line of the pump system.
There are 2 places in the tubing to the tank that consistently have large bubbles. These “bubbles” or air gaps do not seem to travel with the solution even though the solution is being pumped. I believe a check valve will also fix this.

It appears the PFERTZ solution mixture settles out. I can tell that the macros settle to the bottom. I will need to stir the solution each day until i find an automatic solution.

Plants seem to be sprouting a lot more water column roots. (due to higher fer levels most likely)

PUMP OUTPUT TEST (Sunday water change day)
pump dosed 9.8ml during the day
9.8/19 =.51ml per min average actual pump output
this is pretty dang close to the 9.72 i was shooting for :)
but its .4 lower then what it should be if the pump was actually pumping .54ml per min

I am very happy with this setup! It seems to greatly benefit the tank and it takes a lot of unnecessary pressure off of me. I would go as far as to say an auto dosing setup should be treated like co2 for those who want the best planted tank possible (a must have). Its simple to set up, pretty easy to calibrate, and keeps your ferts more steady and consistent then any human could. If you use dry ferts to mix your own solution it will pay for itself in very little time if you are accustomed to using liquids. I can already tell I will be buying another pump very soon so I can have a fully automated fert setup. I would go for automatic water change system next since its the last thing I have to manually do (other then trim and clean the glass) but I live in an upstairs apartment and it would be just silly to try and rig something like that up here. This auto dosing setup has gotten rid of a huge source for human error witch I believe will make my tank/this hobby more enjoyable for me due to the fact I will be able to spend more time aquascaping, trimming, and just being creative/artistic rather then trying to correct then re-correct fert issues in the tank. Unbalanced or inconsistent ferts can lead to so many issues its not even funny. Time and time again I would spend weeks or months trying to figure out then correct one issue only to find out that I had created another. I am hopeful this will eliminate most if not all of the algae/plant issues I have battled in the past. If it does not eliminate all the issues at least I will be able to make slight adjustments then test them over long periods of time with constancy instead of changing something then forgetting to dose 2 out of the three days or having to dose 2 days in a row or pumps becoming clogged and not noticing for a few weeks or whatever.

Trial 4 (2 day output trial)
Pump output was 20.5
20.5 /2= 10.25
10.25 day output is very close to what I expected. The accuracy of this pump is very good.

Plant growth is very accelerated and healthy. All existing algae issues that were present prior to setting up this auto dosing method are gone. The green algae increase I saw last week was only temporary and is no longer happening.

My water is cloudy again this week near water change day. I will run some carbon for a week or two at week 5. The water also seems to have a stronger smell then usual. I know I cant leave carbon in the filter because it pulls the nutrients out of the water but I want to get the water nice and polished to see if their may be some other issue going on that is causing the small and cloudiness. I did add a new piece of wood and a ton of baby tears so the cloudiness may have something to do with that. I have no idea why the smell has gotten so much stronger.

The check valve cured the issue of the ferts settling back into the hose. But there are still large, unmoving air pockets in the hose. I will purge the lines to see if that can get the air pockets out and keep them out. I worry that crystals may from in these air pockets causing a restriction on the flow.
This system is working great. No problems arose this week so I have no tips for someone setting up a system like this. All I have to say is this has been SOOOOOOOOOO worth the 98 bucks it cost complete with timer. I will be purchasing a second pump at the end of this month.

I started to build a DIY stirrer. I read a lot of things about how to do it and i have decided I'm going to build one out of an old broken computer hard drive. I'm a computer technician so i have a lot of these guys lying around and all the parts you need are right there. Motor, magnet, even a cover so i can set the fert container on top. Should be a fun project but i haven't had much time to get into it other then ripping apart one of the broken drives and figuring out how to power it. I am a little worried that the HD motor may spin to fast but I'm thinking i might be able to use a fan speed controller to slow it down (i hope)

Lastly, I am now thinking of replacing my lighting. My main CF fixture is pretty loud and really not the right size for the tank. Also cf bulbs don't last very long and are expensive to replace. I dont know..... well see it may be time for super high light :)

Trail 5

P.S. Eventually I plan on talking about my c02 setup and mixing dry ferts for auto dosing in this tread as well.

480 Posts
I have a few questions. How noisy is the pump when it's running? and does it just run off of 120v or does it require a voltage adapter?

9,774 Posts
Nice write up and may be soemthing for me to consider in the upcoming future. Once thing to consider is to put a check valve in line which should keep the mixture from flowing backwards back in to the container.
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