Maintaining your water system properly is one of the most fundamental considerations when it comes to hydroponics.
Water plays the leading role of dissolving and transporting nutrients to the plants. It also assists in dissolving any harmful contamination. The amount of nutrients, having stable pH levels and water cleanliness are crucial factors to sustainable growth for hydroponics.
Changing the water at specific intervals will help ensure these factors can be achieved. Not only that but it also prevents over-accumulation of nutrients, bacteria, and fungi. It will also give you the chance to restart and clean out your system.
Now that we understand some important issues, let’s have a look at how often to change hydroponic water
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How Often to Change Your Hydroponic Water?
Depending on the capacity of your system, you should allow around 2-3 weeks between full water changes. Technically speaking, it’s not just the water that you need to replace but the complete solution that has been added to begin with.
Once the volume of added top-off water equals the total volume of the tank, it’s time to change the hydroponic solution. This is to aid in replenishing any lost water through evaporation, transpiration, or plant water consumption.
In some cases, it may be necessary to change more frequently based on a few factors. These include struggling to maintain sufficient pH levels as well as electrical conductivity.
After all, the whole concept of hydroponics is about providing adequate water whilst maintaining control of specific added elements.
One of the biggest advantages of going through this process is knowing and understanding what you actually added into the water. It’s also a chance to correct any errors that you may have made within the previous time period.
Why Should You Change the Water of Your Hydroponic System?
Now that we have a idea about how often to change hydroponic water, we should also know “why?”.
Changing the water in your hydroponic system is one of the most important tasks to partake in during the whole process. The composition of the solution changes over time, meaning nutrients, pH, EC levels, etc can become out of balance and need to be corrected over time.
The bottom line is, a changeover helps to promote healthy growth and development for the plants. Making sure the nutrients get to the plants via the water system is crucial.
A few important things to consider when creating your setup to assist with a changeover are:
To Set Up Proper Water Control Mechanism
Setting up proper water control mechanisms could be the make or break for your system. The biggest reason you’d want these functions is so you have total control of what goes in your solution and exactly how it is distributed.
For example, if you join your reservoirs or buckets together using flow pipes, it’s a good idea to add in water control taps. This will ensure that the correct amounts of solution get to the right places at the right time.
As far as mechanical controls are concerned, the sky’s the limit. You can purchase electronic pumps with timers that ensure that solution distribution is delivered with optimal timing.
Then there’s water temperature controls which will ensure that the temperature is perfected for optimal growth. These are just some basic tools to help.
To Prevent Biofilm Accumulation
Biofilm accumulation in a nutshell is the build up of algae that forms on the surface. It’s pretty nasty stuff if you leave it unattended for too long. It can really set you back in the long run. This accumulation causes what’s known as phytopathogen infections in your plants.
This will almost definitely see them suffer from things like parasites, fungi and specific types of viruses. By changing the water of your hydroponic system, you are giving your plants the absolute best chance of survival. It also gives you the opportunity to start a fresh and correct any imbalances you had made in your previous cycle.
Factors Impacting Water Changing Schedule for Hydroponics
There are multiple varying factors that will have an impact on your water changing schedule. It will also help you understand how often To change hydroponic water more clearly. These include:
Evaporation
Reducing the effects of evaporation is an important part of the hydroponics balancing act. One of the prime factors for evaporation is heat.
Having too much heat in your grow room will lead to unwanted evaporation. This will cause your plants to drink more water than they usually would in a cooler setting. It’s ideal to do regular checks on your reservoir to make sure that it is covered.
This will help prevent any unnecessary loss of water as well as reduce algae from contaminating the water.
Plant Types and Density
As you are well aware, plants come in various types and densities. Different types of plants require different amounts of water. This factor will impact water consumption which as a result will influence your water changing schedule.
As a general rule of thumb, use this as a guide at a bare minimum and adjust a needed:
- Small plants: 1/2 gallon of water per plant.
- Medium sized plants: 1 – 1/12 gallons of water per plant.
- Large plants: 2 1/2 gallons of water per plant.
Adding to size, another element to consider is a plant’s natural environment and ecosystem.
A bit of research as well as trial and error will be required. For example, you could be growing a tropical plant. You will need to adjust water levels accordingly.
If you live in a:
- Dry climate – It’ll need a little extra water.
- Tropical climate – You may not need to provide extra water
- Temperate climate – The dryness could make the water evaporate and you may need to top up.
Size of water reservoirs
The size of your water reservoirs can impact your water changing schedules immensely. If you have smaller tanks, they will dry out faster, therefore they will need to be replenished more often.
On the other end of the scale, the bigger they are, the more they hold, therefore the change over time will be less frequent. This is of course based on your setup being planned out properly.
Topping off your solution
Topping off your solution involves replenishing either water or nutrients depending on the levels of PPM (Parts Per Million) or EC (Electrical Conductivity). When carrying out this process, your water changing schedule could be affected.
You may find that the plants are consuming more of the water and solution. This could be due to a number of aspects like climate or plant size. If this is the case then the water will need to be changed more frequently.
Perfect pH Levels
Each plant requires a specific pH level for it to be able to grow and thrive. Having an optimal pH level specific to each plant is important because it affects nutrient availability for your growing plants.
A pH level that is too high or low can prevent nutrient uptake and lead to deficiencies. The plant will try to consume more nutrients which in turn will make water changeover more frequent.
Types of Water Changes for Hydroponics
Beside knowing how often to change hydroponic water, it is also important to know in what way you should do it.
Full Water Changes
Opting for a full water change and flush can be decided by one underlying consideration. That is, once you have topped off your reservoir enough times to fill it completely.
It is recommended that you change out the water every 2-3 weeks. It’s also a good idea to give the reservoir a really good flush and scrub if necessary. This process will also help to prevent over-accumulation of nutrients, bacteria, and fungi.
Topping of the Tank
Topping off your solution is a key task required to help keep the balance between water and nutrients within your hydroponic systems reservoir.
As your plants consume the water and nutrients, the strength of the nutrients will change. They can become diluted. This will require you to add either more solution or more water.
How much water or nutrients will depend on a few things. It will depend on what the PPM or the EC is. If the PPM or EC is higher than when you began, you should add water. If they are lower then you should add nutrients.
As a rule of thumb, the strength of the nutrients should be between 800 to 1500 PPM.
How to Change the Water for Your Hydroponic Setup?
Changing the water for your hydroponic setup doesn’t have to be a difficult task. It can be simplified by following some specific guidelines. Everyone’s setup may be a little different depending on the layout.
This method will be based on an RDWC. (Recirculating Deep Water Culture) system.. Let’s have a look at the process step by step.
Before beginning this process, it’s a good idea to test pH and EC levels so you know what to add when you have completed the flush.
- Step 1: Disconnect any power supply to pumps/air agitation pumps.
- Step 2: Close off any isolation valves you have within your system.
- Step 3: Direct all flow of water to flush hose
- Step 4: Connect a hose to the reservoir water change valve. (If you don’t already have one within your setup) Make sure that the other end of the hose is directed somewhere where you are happy for the water to drain to. Eg: A watering can, sink/drainage, garden.
- Step 5: Open up that valve and plug the pump back in.
- Step 6: Begin pumping out the water until there is just enough in the bottom to not let the pump run dry.
- Step 7: Turn off the pump.
- Step 8: There will more than likely be some residue at the bottom. You can scoop most of it and use a sponge to swipe it all away.
- Note* It is possible to remove the hose and completely flush out the reservoir/bucket. If this is the case, use clean water and a few capfuls of household bleach. Keep in mind to wash away any excess bleach to prevent contamination in your clean water.
- Step 9: Fill your reservoir with clean water as well as required nutrients. Include any other additives to ensure the pH and EC levels are balanced.
The general concept will be similar for most systems.. You may just have some different valves, reservoir types and pumps. The idea is to remove as much water as possible, and refill it whilst adding required nutrients.
Not to over complicate the process but there are a few extra things that you could do to make the job even easier.
For example, you could purchase a small/medium size battery powered hand pump. They cost anywhere between $9-$50. There are some great quality pumps at mid range which cost only about $20.
You could also plumb a tap drain into the bottom of each bucket leading to a single main flush valve. This would enable you to just open them all up and drain without solely relying on a pump. It would also save a lot of time draining each bucket into one. That’s a DIY worth looking into!
How to Test to Determine the Change of Water?
Just because we know how often To change hydroponic water doesn’t mean we should follow it blindly, testing the water may also help us take accurate decision.
pH testing
pH levels can help determine whether something is acidic, neutral or alkaline. A pH scale ranges from 0-14. On the lower end of the scale, 0 represents being most acidic. On the other end, 14 represents being most alkaline.
The neutral point is represented by the number 7. In this case, we are talking about the water in your hydroponic systems reservoir.
Making sure to have the right pH levels is imperative to your system being efficient and effective. It’s desirable to keep the pH levels between 5.5-7 for most plants.
Having the wrong pH level can result in too little or too much of certain nutrients. For example:
- pH levels under 5 – plants can develop magnesium and calcium deficiencies or copper and iron toxicity.
- pH levels over 6/6.5 – can cause iron deficiency.
A simple pH testing kit can be purchased online, most hydroponic stores and most hardware type stores. The test itself is quite simple.
All that is required is to fill a small vial with a sample of your nutrient solution. (The vial is usually provided with the test kit, make sure to double check that one is included) Then add the recommended amount of drops of pH sensitive dye to the sample vial.
The color of the sample vial solution should change. Compare the color with a pH color chart to ascertain the pH level of the reservoir. At this point, you can add your pH up or down solution.
If you notice your pH is below 5.8, add a small amount of pH up and test it again. On the other hand, If it is above 6.5, add a small amount of pH down and test again.
EC Testing
EC or Electrical Conductivity gives you an idea of the quantity of available nutrients. More nutrients will give a higher EC reading. It means that there is a higher concentration of dissolved substances deeming the water impure.
The easiest way to determine the EC levels of your hydroponic system is by using a digital meter. The most common and higher quality variant is the Bluelab CF Truncheon.
The way these meters work is by measuring the EC by using the electrodes usually located at the base of the meter. Simply dip the end into the solution and check the digital reading.
If the EC value is too high, add clean water to the reservoir. If the EC value is too low, add either liquid fertilizer, plant food, or nutrients.
Here is a handy table with preferred pH and EC levels for a range of common fruits, vegetables and herbs.
| Plant | pH | EC | PPM |
| (Preferred over PPM) | |||
| Basil | 5.5-6.5 | 1.0-1.6 | 700-1120 |
| Bean (Common) | 6.0-6.0 | 1.8-2.4 | 1400-2800 |
| Bean (Broad) | 6.0-6.5 | 1.8-2.4 | 1400-1800 |
| Bell Peppers | 6.0-6.7 | 1.8-2.8 | 1400-2000 |
| Broccoli | 6.0-6.5 | 2.8-3.5 | 1960-2450 |
| Brussell Sprouts | 6.5-7.5 | 2.5-3.0 | 1750-2100 |
| Cabbage | 6.5-7.0 | 2.5-3.0 | 1750-2100 |
| Cauliflower | 6.0-7.0 | 0.5-2.0 | 1050-1400 |
| Celery | 6.3-6.7 | 1.8-2.4 | 1260-1680 |
| Chives | 6.0-6.5 | 1.8-2.4 | 1260-1680 |
| Cilantro | 6.5 – 6.7 | 1.3-1.8 | 910-1260 |
| Cucumber | 5.8-6.0 | 1.7-2.5 | 1190-1750 |
| Eggplant | 5.5-6.5 | 2.5-3.5 | 1750-2450 |
| Lavender | 6.4-6.8 | 1.0-1.4 | 700-980 |
| Lemon Balm | 5.5-6.5 | 1.0-1.6 | 700-1120 |
| Lettuce | 5.5-6.5 | 0.8-1.2 | 560-840 |
| Melon | 5.5-6.0 | 2.0-2.5 | 1400-1750 |
| Mint | 5.5-6.0 | 2.0-2.4 | 1400-1680 |
| Pak-choi | 7 | 1.5-2.0 | 1050-1400 |
| Parsley | 5.5-6.0 | 0.8-1.8 | 560-1260 |
| Pea | 6.0-7.0 | 0.8-1.8 | 580-1260 |
| Peas (Sugar) | 6.0-6.8 | 0.8-1.9 | 580-1261 |
| Peppers (Bell) | 6.0-6.5 | 2.0-2.5 | 1400-1750 |
| Peppers (Hot) | 6.0-6.5 | 2.0-3.5 | 1400-2450 |
| Pumpkin | 5.5-7.5 | 1.8-2.4 | 1260-1680 |
| Sage | 5.5-6.5 | 1.0-1.6 | 700-1120 |
| Spinach | 5.5-6.6 | 1.8-2.3 | 1260-1610 |
| Squash | 5.0-6.5 | 1.8-2.4 | 1260-1680 |
| Sunflower | 5.5-6.5 | 1.2-1.8 | 840-1260 |
| Strawberries | 5.0-5.5 | 1.0-1.4 | 500-700 |
| Swiss Chard | 6.0-6.5 | 1.8-2.3 | 1260-1610 |
| Thyme | 5.5-7.0 | 0.8-1.6 | 560-1120 |
| Tomato | 5.5-6.5 | 2.0-5.0 | 1400-3500 |
| Watercress | 6.5-6.8 | 0.4-1.8 | 280-1260 |
| Watermelon | 5.8 | 1.5-2.4 | 1050-1680 |
| Zucchini | 6.0 | 1.8-2.4 | 1260-1680 |
Can Hydroponic Plants Be Overwatered or Drown?
If your hydroponic system is set up properly then there is only a very slim chance that your plants may drown. The way hydroponics works is that the water which is used is constantly oxygenated, circulated, filtered and refreshed.
Having air pumps installed and using air stones help with oxygenation also. This means that the water levels should never really reach a high enough point where your plants are fully submerged into it.
Of course there are ways that it is possible. Like having a build up of algae for example. Algae can also photosynthesize and whilst conducting this process, they can use the plants potential oxygen for their own growth.
Plants will compete and try to use their energy to suck water up through their roots. This requires oxygen to do so. If oxygen levels decrease, the water won’t reach the roots.
If it can’t reach the roots, it cannot help the plant grow to its full potential. This is when you may see remnants of water sitting in the root zone which you could call ‘overwatering’.
This is why it’s important to watch out for algae and clean it away if it starts showing up.
Other reasons to change the hydroponic solution
Some other reasons why it is ideal to change out the solution in your hydroponic system are:
- The solution can become concentrated as the water evaporates. Fresh water should be added if this is the case.
- It prevents too much build up of nutrients, bacteria, and fungi.
- Flushing and reloading will allow you to adjust pH and EC levels.
Conclusion
At the end of the day, changing the water in your hydroponic system is a necessary task that should be performed according to a schedule. Regardless of the type of setup, there is every chance that it could build up with algae and bacteria.
Also, giving your reservoirs a really good flush only makes your job easier for the next change over. It allows you the chance to reload and adjust any errors that you may have made during the previous cycle. We hope that this guide regarding “how often To change hydroponic water” has been helpful in your journey to mastering the art of hydroponics. Happy Growing!
