Filtering water is essential for eliminating contaminants that can harm plants, maintaining pH balance, and preventing mineral build-up in pumps, tubes, and spray heads.
Water purity is also important when adding nutrients, as hydroponics manufacturers provide guidelines based on zero parts per million (PPM) of dissolved solids, even though municipal water’s baseline is often as high as 300 PPM or more.
Filtration can thus help by regulating nutrients, contaminants, and variables that could otherwise disrupt the aerobic conditions for this form of horticulture.
Although choosing the best option may seem difficult, its really not and you too can reap the benefits by focusing on your hydroponics garden needs. We are going to walk you through it.
Stages of Filtration for reverse osmosis
Due to the high costs of other methods like distillation and electro-dialysis, reverse osmosis is the most common type of filtration. With lower energy costs and relatively simple installation, such filtration systems are especially well-suited to small operations.
Reverse osmosis includes 5 basic stages of filtering, and uses high pressure to force water molecules through an extremely fine membrane.
- First, a spun sediment filter removes 90% of large particulates.
- Then, a highly porous carbon block pre-filter removes chemicals like chlorine.
- One or more osmotic membranes remove dissolved solids and lowers the level of contaminant parts per million (PPM) by 95% or more.
- Next, a carbon post-filter re-mineralizes the now-acidic water to balance the pH.
- Finally, water is sometimes treated with UV or other filters to further purify it.
These stages work together to ensure water that can provide a healthy, aerobic environment for plants. At the end, purified water enters a storage tank, while contaminants leave as wastewater.
Selecting the Best Model
When it comes to choosing a filtration system, consider your options. Independent de-chlorination and sediment filters like HydroLogic’s fully-assembled Small Boy, Tall Boy, and Big Boy models represent simple options with easy set-up and no wastewater. These two-stage units are easy to install onto your hose, but instantly remove 99% of chlorine and most sediments. For a full reverse osmosis system, look for a solid basis; that means at least 5 stages and 3 pre-filters including 2 carbon blocks and a sediment filter to protect the main osmotic membrane.
When choosing a particular model, start by determining the ideal size based on available storage, current water consumption, and future needs. Although most growers tend to choose a smaller capacity for cost reasons, remember that actual outputs are generally 75% of the advertised rate. However, in a recent test from Grozine, HydroLogic filters outperformed competitors by almost double. Operations using well water will also need to choose larger RO membranes as smaller ones may not be able to handle associated higher cleaning loads.
Smaller operations will appreciate Active Aqua’s two-stage model for its on-demand purification of 50 gallons per day (GPD). Similarly, HydroLogic sells a portable 75 GPD Micro that includes an easily-replaceable, high-quality KDF carbon filter with a high rejection reverse osmosis membrane and various optional add-ons.
However, since most growers underestimate their needs, both Active Aqua and HydroLogic’s convenient 100 GPD models may be better small-scale options that can be scaled up later using more advanced replacement filters and parts. HydroLogic’s Stealth line is specifically designed to balance the nutrient uptake and microorganism health of hydroponics. For instance, the Stealth RO 200 uses two 150 GPD membranes to produce as much as 300 gallons per day with half as much waste as similar systems. Similarly, Active Aqua’s 100 GPD model relies upon 1-micron sediment filtration and a TFC membrane to ensure high efficiency, flow, and rejection rates.
For larger operations, HydroLogic also offers the Evolution RO 1000 high flow system with two high-flow RO membranes. Although it can handle as much as 1,000 gallons per day, the Evolution keeps waste low, with a mere gallon of waste per gallon of water purified. An optional Pre-Evolution pre-filter adds 2 extra stages to help eliminate more contaminants and so extend the life of filters and the larger system alike.
No matter what model you choose, ensure that components are made according to industry standards and can be easily replaced, with at least 6 to 9 month lifespans for filters and 2 to 3 years for membranes. In addition, look for models with high-quality materials, including thin film composite (TFC) membranes and carbon block filters rather than granular activated alternatives that tend to create clogs. Active Aqua and HydroLogic fit the bill on both accounts with their high-quality, reasonably-priced replacement filters and reverse osmosis membranes. Fundamentally, remember that a lower price often equals lower quality with shorter filter and membrane life, lower quality tanks, and overall ineffective filtration.
Choosing the Right Components
Despite the benefits of reverse osmosis, individual growers will face issues like high levels of contaminants, low water pressure, and even the basic problem of a 3:1 ratio of waste to purified water. Adapting existing or incorporating new components can help address just such problems.
- Water pressure booster pump to improve RO throughput and end tap pressures.
- Pleated and poly-blown sediment filters remove more and smaller particulates, respectively.
- Coconut green carbon filters deliver better performance, while catalytic ones clean heavy metals and bacteria.
- Various specialized membranes help raise or lower flow or rejection rates.
- Similarly, water restrictors and booster pumps help regulate water pressure.
- Add-ons like eco-waste reducers can address water waste by raising efficiency.
- Algae blocks over filters screen out light to minimize algae growth and related inefficiencies.
- Stainless steel ultraviolet (UV) filters and KDF85 filters eliminate microorganisms.
- And TDS monitors and de-ionization cartridges monitor and remove nitrates, phosphates, and silicates.
The options for customization make it possible to directly tailor your filtration system to your hydroponic garden’s needs. So, although the initial investment for a filtration system may be relatively high, the myriad of benefits will quickly make it a worthwhile one.
Reverse osmosis filtration systems are thus powerful tools for gardeners of all stripes and especially those whose gardens rely upon ultra-pure water. Filtering makes it possible to control variables, manage nutrient solutions, and ensure consistent yields over time for hydroponics. So, consider using this important asset for your own operation—as a powerful substrate foundation for a clean, consistent, and vibrant hydroponic system.
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