Time to Change Your Hydroponic Reservoir: Avoid Salt Lockup

Hydroponic Nutrient Reservoir
The water in this reservoir is not fit for a hydroponic system.

Reservoir changes are an essential part to all hydroponic systems.  The reservoir is where your oxygenated water and nutrient solution rests in between feedings.  You can read up on res changes if you are unfamiliar with them.  Depending on the size of your reservoir, hydroponic growing system, and nutrient solution your reservoir should be changed every 7-14 days.  Recirculating hydroponic systems need to be monitored closely for signs indicating its time for a res change.  If you procrastinate too long, your plants may become victim to the dreaded salt lock up.  Look for these 5 signs to ensure you don’t wait too long!

1. Discolored Reservoir Water – Hydroponic systems usually have nutrients and potentially an insecticide like Azamax mixed into the reservoir.  After recirculation the solution picks up extra things you do not want to continually recirculate through your system.  If your nutrient solution is not the color it was after you mixed it, it may be time for a res change.

2.Dead bugs – Dead bugs can have germs and carry diseases you do not want transfered to your plants.  If you see floating dead bugs in your reservoir water, change it!

3. Wrong PH/High PPM – If the PH of your water is too high, you could damage your plant’s root system.  You can get products that will adjust your PH, but use them in moderation.  There could be a greater problem you are missing out on if you continually lower your PH with solutions.  A high PPM can lead to nutrient burns and salt lockouts.  You can add plain water to offset a high PPM, but a reservoir change is in place if you made your nutrient solution too strong.

4. Plants are deficient in one nutrient, but over fertilized by another – Using multi part nutrient solutions can give a grower a lot of precision.  If you notice your plants are showing signs of deficiency for potassium, but look over fertilized, they could just need a different ratio of nutrients.  A reservoir change will allow you to start your nutrient mix from a fresh pallet.

5. Two Week Rule – If you have been using the same res water for more than two weeks, its probably time for a change.  Letting your res water evaporate and get low can also spike your PPM.  Don’t let a huge reservoir fool you!  You still need to monitor your PH and PPM because the nutrients do not evaporate out of the water.

Collect Rainwater to Fill Your Reservoir

A large hydroponic system can use a lot of water.  Most indoor gardeners are concerned about the environment and wan’t to reduce their carbon footprint.  Growing your own food at home is a great way to be green.  Gardeners don’t want to be consuming more than they have to because that would be completely counter productive.  There are ways to get your water for free and recycle at the same time.  You can use any sturdy food safe container that can withstand your area’s outdoor conditions as a reservoir for rainwater.

Depending on when it rains in your area you may need to plan to catch the rain water during its season.  Collecting rainwater is easy and even though it may not cover all your water uses, it will certainly reduce the amount of water you pull from your city or well.  You don’t have to be an indoor gardener to have uses for rain water, although you should run your water through a reverse osmosis system to make sure its clean.  RO water is better gardeners anyway because you know exactly what you are putting in.  If you would just like to go buy a water collection system your local hydroponics shop should have something you can use.   The water barrels at the hydroponic store are usually 55 gallon barrels with a lid.

I plan to write a detailed guide in the near future on how to start your own homemade rain collection system.  In the meantime, Hydroponic Economics will be accepting pictures of anyone else who has started a rainwater collection system.  Send your pictures to mailbox@hydroponiceconomics.com and you may be featured on the website!

How Often Should You Change Your Water Reservoir?

QUICK ANSWER : Every Seven Days

Longer Answer: When you are trying to decide when to change your nutrient reservoir in your hydroponic recirculation system, there are a few things to consider.  The size of your reservoir, the amount of nutrients remaining in the solution, ph, and how clean the water is. If your water looks gross, it probably is gross.  Gross water = Gross plants.  Gross deserves a capital G for that equation.

The bigger your reservoir the further you can go between res changes(Res change is short for water/nutrient reservoir change ).  Big reservoirs may be more forgiving then a small reservoir.  Small reservoirs may change by hundreds of ppm in a single day.  Hydroponic systems require close monitoring of nutrient levels to avoid burning plants.  If your reservoir loses water to evaporation make sure to top it off with plain water or a very low ppm solution.  Res changes mostly apply to recirculating systems.  Non-recirculating or “run to waste” hydroponic systems only require you to change the solution every two weeks.  The nutrient solution stays clean and the PH is maintained in a non-recirculating system.  The most important part of a good hydroponic system is a clean nutrient reservoir.

A clean nutrient reservoir loaded with Earth Juice Bloom and Azamax