Home > Products > Hydroponic Dosers >


Alternative Views:


The new MultiGrow is your all-in-one, multiple grow area controller. The Multi is designed to grow with you… starting with two greenhouses but want to eventually double that? Start with a simple Multi and expand as needed. Due to the endless configurations and customization of the Multi, please contact us for a quote.


The Multigrow controller is a modular system that can control the climate of up to 8 greenhouse/warehouse compartments in addition to managing other functions like fertigation, hydroponic dosing and environment monitoring; the best part is you only pay for the functions you will be using. You can receive alarms by SMS or email and the controller has remote access using a wi-fi tablet or smart phone. Although the climate control has a high level of functionality, many of the more complex settings are preset in the factory and you will get excellent results without changing these. They are provided for the perfectionists who would be frustrated if they were not available. Luckily, we provide "restore points" so if you change some advanced settings and don't get the results you expected it is simple to put the settings back to how they were.

The Multigrow is available in the following formats:

  1. A large touch screen format which is proving to be the most popular as it provides a larger, high resolution, high brightness full color touch interface. This is shown in the picture above.
  2. A screenless controller that is connected to a desktop LCD monitor, keyboard and mouse. This is a low cost option for situations that have a clean, office like environment in which to locate the MULTI. Alternatively, a wi-fi access point can be added to allow a tablet such as an iPad to be used as the user interface.

All of the above options can be connected to a computer network by ethernet cable or wi-fi and the controller can be accessed by any computer on the network that has a standard web browser. In larger installations it is convenient to set up an office computer with a number of screens (perhaps 3 or more) so that a different aspect can be displayed on each screen.

Tablet interface

Any of the above options can interface with an iPad or Android Tablet device through the network connection and if the wi-fi is set up to provide coverage to the main areas of the farm this provides an extremely useful interface as the iPad can be carried around to where sensors etc are located to conveniently perform calibrations and settings changes.

  • Choice of either a simple or advanced compartment manager. The advanced manager, allows influences for humidity and solar radiation. These influences affect vent opening and heating in order to manage RH as well as temperature. Both managers allow temperature ramping between the 5 available time periods.
  • Vent management - simple or advanced - this provides vent cracking proportional to humidity, together with wind and rain overrides. The advanced manager also allows PID control which is used to eliminate error from the temperature target. Outside influences are taken into account to get some pre-act or anticipatory control so that vents etc start to react when outside conditions first change rather than waiting for the inside temperature to change before reacting. A maximum of 32 vents (or 6 vents per compartment) may be assigned.
  • Extraction fan management. Up to 5 fan banks per compartment can be installed, wet wall (pad) management is also available. Smart control of fans such as cycling of first group to start to avoid crop streaking. Also, storm bracing can be used to reduce pressure in house to avoid skin flap causing damage in severe storms.
  • Stir fan (HAF) management (up to 2 fan groups per compartment). Set by time period with rules to activate for humidity, temperature, CO2 injection, fogging
  • Heating - either on/off or heat-pump or proportional hot water heating using a 3 way modulating valve. With hot water heating a minimum pipe temperature may be used for humidity control and this has influences for solar and humidity. A special heat pump setting is available to switch between heating, cooling and dehumidification and to act as a thermostat to the heat-pump. Boiler heat demand and transport pipe management is also available.
  • Fogging may be used to provide evaporative cooling and/or humidification. The settings for fogging are rule based so that it fogging is activated when the temperature is above a set level providing the humidity is not already excessive. A second rule may be used to also start the fogging when the humidity is below a set level providing the temperature is not too low. The fog ON time (puff size) is proportional to the temperature or humidity error giving excellent control. Separate time periods may be set for fogging. Up to 16 fogging valves may be used with a maximum of 4 valves per compartment. Pipe discharge function also possible.
  • Watering /sprinkler /misting control by radiation sum/timer/time-of-day is available for watering and misting.
  • Shade and energy screens may be used to reduce the radiation load on the crop and also to reduce heat loss at night. Up to 3 screens per compartment may be assigned. A clever algorithm calculates the best combination of screens for the conditions. Screens can be set to crack before opening to avoid sudden shock to the crop by spilling cold air. The screens can also proportionally crack for high humidity or temperature or even to melt snow and ice on the roof.
  • CO2 injection. A sophisticated algorithm is used to allow maximum use to be made of injected CO2 without excessive wastage. Again, the advanced settings come preset and you will get excellent results without changing these. For the more advanced user the influences are as follows:- Proportional reduction in CO2 concentration and injection for 1) Lack of solar radiation 2) low temperature 3) vents partially open 4) wind with vents open 5) excessive VPD/HD.
  • Lighting control for either supplemental and or timed light switching. Up to two banks of lights per compartment with phased turn on and minimum cool down period.

Batch dosing refers to the situation where you have a large mixing tank to hold the irrigation water. The tank batch cycle involves filling the tank. stirring and dosing and then irrigating the crop as required by timer or solar radiation summer.

Systems like NFT and DFT do not require this batch processing as they are usually continuously recycled. The tank is continuously receiving drain water back from the crop and as the water level drops due to transpiration, a simple float valve opens to allow make-up water to enter. This may drop the EC a little and change the pH and so it is normal to have a simple on-demand hydroponic doser continuously monitoring the EC and pH and operating small pumps or gravity fed valves to add nutrient and/or pH stock solutions to correct the change.

The MULTI from Autogrow supports up to 8 batched or simple dosed tanks in any combination.

The doser will not adjust individual elements in the mixture and so it is possible for these to gradually get out of balance. In particular, elements like sodium which enter via the water will build up and may reach toxic levels. To avoid this the tank will need to be dumped periodically - hopefully, the grower will use the water for irrigating some outdoor crops rather than allowing it to pollute the environment. Commercial growers will take samples from their mix tank periodically (perhaps weekly) to send to a laboratory for analysis. This will avoid them wasting water and nutrient unnecessarily.

As the crop matures it is common for the recipe to change. The MULTI has the ability to dose up to 10 different stock solutions in varying ratio. For example, 100% A, plus 80% B, plus 60% C etc. These ratios are then easily changed so that the recipe always meets the needs of the crop.

When determining sizing of dosing pumps there are a few considerations.

  1. The nutrient stock solution is normally mixed to be approximately at a strength of 100:1. i.e. 1 part of A and one part of B will be diluted with 100 parts of water to give approximately the correct EC
  2. The large tank and grow benches will hold a lot of water. When filled with fresh water the initial dosing will be also very large but once dosed up the maintenance doser only has to top up nutrients etc as they are used by the crop. For this reason it is often arranged for the initial dose to be done manually and the dosing equipment is then only used to maintain the correct EC and pH. If this is done much smaller pumps and valves can be used for dosing.
  3. When dosing an empty tank, bear in mind that adding the nutrients to bring up the EC will have the side effect of lowering the pH. Be careful not to lower the pH too much before adding nutrients or you may find that the pH falls too low once the nutrients are added.
  4. If you install pumps that are too small they will have to do a lot of work and will wear out quickly.