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Discussion Starter · #1 ·
I am looking to go the autodosing route. I am currently on a 38 gal, and will be upgrading to 70-80 gal (custom).

I need to autodose inline, as the goal is nothing over the rimless tank.

The general consensus seems the be the best quality way of doing it, is with peristalic pumps. Cost being the only draw back.

Well, I need to pick up two of these bad boys (one micro, one macro) and I am unsure what brand/flow/rate/WHATEVA to go with.

My current solutions are fairly dense (but do not settle). 5ml of each, every other day. With the same mix, it would take 10 ml for the 80 gallon tank.
 

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Discussion Starter · #3 ·
are there advantages between larger and smaller diameter tubing? rpms of the motor? I saw two people give bad reviews about the SP100, which seems to not only be the most economical, but the closest to our needs.

James
 

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Discussion Starter · #4 ·
And why do the fluids apparently degrade in water pumps, but not using the peristalic pump?
 

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I need to autodose inline, as the goal is nothing over the rimless tank.

The general consensus seems the be the best quality way of doing it, is with peristalic pumps. Cost being the only draw back.


In theory that should work well, but if you plan to feed them into your filter outlet, keep in mind that the back pressure can slowly push tank water into your dosing bottle. Using checkvalves can be problematic, due to the slow flow rate, and the tendency to cake up with the fertilizers.

Well, I need to pick up two of these bad boys (one micro, one macro) and I am unsure what brand/flow/rate/WHATEVA to go with.

Can't go wrong with APT:

http://aptinstruments.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=AI&Category_Code=P2


Well... not sure about that one. They are comparatively cheap, but some of them do have their issue. I got one that regularly stripped out the plastic rotor, and after a year or so of frustration got it exchanged. Another one I have sometimes doesn't start up, unless I whack it a bit. Great value if you get a 100% working one! If quality is your main requirement, you might also look at some other peristaltic pump dosers.

are there advantages between larger and smaller diameter tubing? rpms of the motor? I saw two people give bad reviews about the SP100, which seems to not only be the most economical, but the closest to our needs.

It all depends on how much you want to dose. Read at the website the various flow rates, and figure out how that translates into minutes. Like if a certain speed & diameter delivers one ml/min, and you need 10ml, you would run it for 10 minutes, etc. Keep in mind that the claimed and actual flow rate can be somewhat different.

And why do the fluids apparently degrade in water pumps, but not using the peristalic pump?

In the case of liquid trace ferts like Flourish, you can dose them in full concentration. If you use a different method to dose, like with a little water pump, you will most likely dilute them in water, and that is when they tend to degrade or grow stuff over time.
 

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Discussion Starter · #6 ·
Would running the system on the inlet then be more appropriate? How would one avoid the backwash?

As far as APT, I have read your postings extensively wasserpest (and still struggle to wrap my head about it all.. wish I had u in person in my living room to talk to). The fact that your badmouthing them stops me from getting one... would u suggest another manufacturer?

As to the water pump possibilities....

I dilute my ferts in distilled water so that they all equal a 5ml dosing. (flourish happens not to need to be diluted for me. 5ml straight, is extact EI for 38 gal tank) I have been doing this for some time, and never found them to go rank, even after 2-3 months. (I use fleet enema for P)

As all my local pharmacies carry this stuff for less then $2 a gallon, I wouldnt mind having to pick up a few gallons every 4 months or what ever. Would the fact that my diluting has always been done with distilled water fix the degration issue?

1 gallon = 3785 ml.

If I wanted my gallon of distilled water/fert to last 4 months.. dosing every other day EI.. that would = 60 dosings a gallon = 63ml SINGLE DOSING..

It would be easy to figure out how long the tom water pump needed to be on to run close to 63 ml inline filter w/ checkvalve.

There has to be a way to keep it from going rank.
 

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The inlet pipe on a filter will also have have the force of water being exherted on its walls, so if you would need a check valve delivering fluid into the outlet you would need one on the inlet side too. The head pressure of the water in the pipe alone would exhert a force. But, from my understanding peristaltic pumps always have one roller compressing the tubing that the fluid is delivered through, this is why they can push or pull fluids against a relatively high head pressure when compared to conventional pumps.
What i'm trying to say is that you may not have to use a check valve if the pressure on the delivery hose from the roller negates the back pressure the water in the tank would place into the delivering tubing. Does anyone have any personal experience with this?
 

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Discussion Starter · #8 ·
thats the issue unfortunately. I believe wasserpest has personally experienced the feedback problem.

I believe the water pump has a built in checkvalve. The only problem with the system is that you need to dilute the ferts and it ends up fouling. I really would think using distilled water would negate this?

Heck, I would think the minute ammount of bleach in our tap water would negate the problem.

*($^&#[email protected]$*&^*#@$ just so frustrated...
 

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Don't overthink this... :D

Did I badmouth APT? I thought I said their pumps are a great value. I just responded about the "can't go wrong" part, since you mentioned quality. There are also AquaMedic dosing pumps for about twice the price.

Connecting the peristaltic pump to the inlet will expose it to negative pressure and you might get solution pulled into the tank. Like I said, in theory peristaltic pumps like this stop the flow of solution with their rollers pinching the tubing. I just noted that there is a slight movement of the liquid. Might or might not be an issue for you. I believe there were others that had the same issue, can't remember who it was though. Search for APT and you should find some discussions.

And don't worry about the fouling. If you set it up for two weeks worth, it shouldn't be a big issue anyway. There are also things you can add to the solution, like HCl and perhaps even Excel. Haven't tried it myself.
 

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Dang! ... I wish that I would of never seen that automated aquarium systems site. There goes my next paycheck. :hihi:
 

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Tell me about Left C! I am planning my set up now and hopefully when I return to the states then I can have everything ready to go!
 
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