Hanna's new Ph/TDS Hydro CONTROLLER...

Have you guys seen this yet??

http://www.bestlabdeals.com/HI_9935_Wall_mounting_pH_and_TDS_p/haninmp116.htm

So apparently Hanna has made this budget minded (about $500) controller (and I stress.. CONTROLLER) of ph and TDS. This is not just a meter, it actually corrects low TDS and apparently ph in only one direction. I found this while waiting up for the weekend special at our favorite seed auction, and surfing aimlessly.. maybe I have found the POT of golden nuggets at the end of the green rainbow or maybe its just another POS instrument made by Hanna (who cant seem to make a worth while multi-instrument of any kind that is aimed at the budget hydro market).

My question to my fellow GREEN engineers is whether or not you think at least the concept of this meter is adequate. I know personally using RO water, ph is not always rising. In fact, it quite often shoots low out.. so one way ph correction (which looks like down only on this unit) is not going to cut it. Also, the TDS is a one relay out as well.. which could be adapted to by premixing nutes or using a one part nute mix but the better models have multiple outputs for specific ratio dosing of your nutes (like 1 part micro to 2 parts bloom until PPMs are back in spec).

But on the other hand.. its like $500.. and the next best multi-controller on the market is well over a grand.. closer to $1500 last time I checked.

What do you guys with at least a few hydro runs under your belt think about this controller? Anyone used it?

here is some more info on the meter:
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HI 9935 is a 2-in-1 pH and TDS controller engineered for economical dosage of fertilizer solutions in the hydroponics. HI 9935 measures pH from 0 to 14 and TDS from 0 to 1999 ppm. Two separate setpoints can be user-adjusted from 4 to 7 pH and 900 to 1800 ppm (mg/L). The relays are activated when pH exceeds the setpoint or TDS falls below the desired value. Two pumps or electro-valves can be wired directly to the controller and be powered through the terminals. Independent proportional settings for pH and TDS can be adjusted from 0 to 90 seconds, 0 to 2.0 for pH and 0 to 400 for TDS. A ground probe can be connected to the appropriate terminals to eliminate interference and prolong the pH electrodes life. HI 9935 provides for an alarm relay which is activated in several circumstances. These include when the pH is below the setpoints by the operator-adjustable threshold of 0 to 2.0 pH, or similarly, TDS exceeding the setpoint by a value in the 0 to 400 ppm range. The alarm also goes off if the pH and/or TDS are not corrected within the operator-determined time frames of 1 to 10 minutes. Moreover, the alarm configuration is alterable in a normally-closed or a normally-open state or turned off during maintenance. The fertilization status can be ascertained from a distance through dosage and alarm LEDs. HI 9935 automatically compensates for the temperature effect on TDS. It accepts pH electrodes with a BNC connector and a TDS probe with a DIN connector incorporating a temperature sensor.

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I found it on amazon.com for $480! heres the link - http://www.amazon.com/TDS-controlle...ef=sr_1_154/002-9299272-2790469?ie=UTF8&s=hpc

Someone has got to have an opinion on this!

It is expensive and from what I am reading, does not include the most expensive part, the dosing pumps.

well I have used those $10 vaccume pumps as dosing pumps before.. hell you can use anything as a dosing pump when there is only one part that you are dosing (i.e. critical ratios are not necessary so finite volume pumps are unneccessary).

Five hundred bucks seems expensive but a good ph and tds pen will set you back half that and just think of how nice it would be to be able to have a self correcting res that doses ph and tds itself during the week and even after res changeouts. I have heard of some people who just have a program that empties half the res out every few days and then the res automatically refills and adjusts ph/tds on its own... no more res changeouts! Thats gotta be worth something.

Hanna also has a mini TDS controller that comes with the probe for like $150.. there has got to be someone that agrees that is worth it to never have to measure/mix nutes or TDS again!!

Anybody feeling me on this? Anybody want to see me make the system?

I have found dosing solenoids for $20 at http://www.mcmaster.com/

p/n 7877K55

The TDS mini controller specifically for hydroponics for $125 at: http://www.espchemicals.com/

Thats about it.. make sure you order everything in 12V form.. as many solenoids as chemicals you want to use and then pre-dilute your mixes to all have a 1:1 ratio (i.e. if you are using lucas than dilute the micro 1:1 with RO water) and then whenever TDS falls outside of the band this controller will bring it right back up.

Note that use of solenoids mean your chem tanks must be above the res and at the same level (like on a shelf).

I would like to see you build one

How do these controllers react after recent res changes where the pH and ppm is out of whack from tap water for a short period? Or are these things considered RO only toys?

I am an easy person to convince! I will begin ordering all the stuff.. Im just going to assemble it together in a project box probably no bigger than 5" by 5" and the one 12v power supply that comes with the meter should pop the two solenoids I will use (for lucas formula dosing).

I already have a ph controller that works pretty similar to this that I put together so this will complete the package and get my res about 90% automated.

They are not RO only however if you can afford this I would say buy an RO system first! The meter does dosing in bursts and it should be pretty well able to handle at least 50% res changeouts which is what most ppl do with this type of a setup.

oh and most ppl use the 1/4" RO float valve filling system with this so if you were to say program a timer to pump half the res to a drain every 4 days or something like that it would slowly refill (1/4 line) with RO water automatically and the dosers would adjust PPMs accordingly on the fill.

I can vouch for the ph doser working just fine under these conditions.. though I have to dilute the acid with about 3 parts water with my current system to keep it from overcorrecting.. there is obviously a lag time between when you add something to the res and when it shows up on a meter.. you can compensate for this by adjusting the dose rate (or simply diluting the dose).

I’ve used this unit for a few months and it works flawlessly. It doses either up or down via a selectable switch. It uses a perestalltec pump (spelling?) and doses VERY very slowly so there is no need to dilute the solution, and it never overshoots the set-point. Another good thing is that since it uses a self-checking pump rather than funky solenoid valves you can place the bottle anywhere in the room. No gravity feed involved, no valve boards mounted to the wall. Very clean. Best $400 ever spent.

The problem that I see using solenoid valves for nutrient dosing is getting the A & B parts to flow at the same rate. And, if you’re using a 3 part nutrient at different ratios, forget it!

I recently picked one of these up... Its in the mail atm... Didnt really need it, just was steal and couldnt pass it up. Got a HI 9931 for 80$ shipped to my door. I let you guys know how it works out for me. ATM Im just goin to use it as a meter till chop.

bartender.......I'm just getting interested in automatic dosing and am wondering how the HI 9931 doses? Are you going to hook it up to some pumps?

Uncle Bob......That PH Nanny looks sweet. Its the only controler I've seen with it's own pump built in, nice and clean, not a hodgepodge of components. Did the price included the probe?

wow thanks for the input guys.. i think i may use that prefab unit as my time is at a premium and I already have enough projects.. I do like the parastitic pumps for dosing more than solenoids.. and I already have one ph doser i built myself which is not very professional looking but does do the job.