Indoor Gardening & Hydroponics FAQ's
Author: Aqua Gardening
Date: 14 July 2022

Indoor Gardening & Hydroponics FAQ's

What temperature should I aim for?

Day time 25-28°C, night time 20-23°C.

What humidity should be maintained?

50 - 60% is ideal in a grow tent.

What is the best type of grow light?
  • CFL (Compact Fluorescent) - these lights are the most affordable and come in different light spectrums - they can be run very close to your plants so good for when using in a tight space - you do need to swap the bulbs over from the vegetative spectrum (day light) to the flowering or fruiting spectrum (soft light).
  • CMH (Ceramic Metal Halide) - High in the blue spectrum wavelength compared to other bulbs, these lights are popular during the vegetative growth of crops and plants.
  • HPS (High Powered Sodium) - The most affordable way of having high yields in the short term - these lights do produce heat which depending on your region and season, can be a benefit or a detriment to the inside temperature. Over a longer period, bulbs will need to be replaced regularly and a higher power consumption means they are not the best long-term investment.
  • LED - vast improvements in technology in recent years have meant LEDs are often full spectrum and provide the most efficient light source - good for your plants and good for your power bill! You would not have to change lights over for the different stages of growth. They emit less heat too, which is ideal in warmer regions where heat buildup can be a concern.
What is the best distance between light and plant is best?

Ideal hanging heights would depend on the make and wattage of the light and it is best to follow the manufacturer's specifications. LED and CFL lights can be hung closer to plant canopies, whereas the hotter CMH and HPS will need to be higher unless using a cool tube or sufficient exhaust ventilation.

How long should the grow lights stay for day time?

There are many different timings you can try, however the timings below are tried and proven:

  • Vegetative Phase (1-5 Weeks) = 18 hrs a day.
  • Flowering Phase (8-10 weeks) = 12 hrs a day or 11 hrs a day if it is really hot.
How often should I change my grow lights?

For best results change your grow lights every 3000 hours (every 2 cycles using a single grow light). There is a 10% loss between 3000 - 4000hrs and a 25% loss after 4000hrs of usage. With double ended LEC lamps these hours are 2-3 times longer.

Do I need reflective material on the walls?

No, you don’t have to use reflective material on the walls of your grow tent, however, it is recommended. Using flat white Panda Film or Mylar on your walls results in more light reflection, and therefore in more plant growth.

How much ventilation is necessary?

Enough to maintain the right temperature and humidity in the centre of the canopy. The leaves should maintain a slight flutter during the daylight hours. It is better to have too much ventilation rather than too little. A ventilation system should replace the total volume of air in the grow tent every 2-3 minutes. Please see our grow room fan calculator.

What brand of hydroponic nutrients should I use?

All nutrients will grow plants so it is a matter of personal preference. Some nutrients will be easier to use and less maintenance than others. House & Garden base nutrients are some of the best and easiest to use.

What EC should I aim for in hydroponics?

EC (electrical conductivity) measures the amount of salts in the water. To measure EC, you will need an EC/TDS meter or pen. The EC changes with the growth phase, the grow media and the nutrient brand. As a general guide:

  • Vegetative phase EC: 1.1 - 1.8
  • Flowering phase EC: 1.6 - 2.0
  • Final week EC: 0 - 0.4.
What pH should I maintain for hydroponic plants?

The safest pH range is between 5.5 - 6.5. Above or below this and the plant will not absorb some of the minerals from the hydroponic nutrient. The ultimate pH level for plant absorption is between 5.5 -5.8. This is when all the minerals are available at full strength. In the last 3 weeks of flowering a pH of 6.2 - 6.8 will make more P/K available to your plants.

How often should I water?

Use 10-15% more than the container can hold and water during the daylight cycle. Perlite: 1-2 waters per day to 3-4 feeds a day. Clay balls: 15 min per hour, then 15 min per 2 hours. Coco: 1 water per day till the plants are 30cm high, then 2 per day till 50cm, then 3 per day.


How often should I flush?

Every 7-10 days is recommended when using pure mineral base nutrients (H&G, Cyco, Canna etc.). A small amount of nutrient in flush solution (EC 0.6) will save the plant from any unnecessary stress. Make sure the temperature and pH of the flush water is correct. Do not over flush as this can cause inconsistent PPM/EC/CF levels. A general guide is half the volume of water to the amount of media in the pot. Eg. 50L pot = 25L of flush water.

What causes the tips of the plants to burn?

This can be caused by too much fertiliser (too high EC), too much salt in the water, not enough water, lights too close (too much heat) or not regular flushing. Certain nutrient deficiencies can also cause leaf tip burn.

What causes leaves to turn yellow?
  • Nutrient solution too warm (18-22°C is optimum)
  • Low oxygen levels due to lack of aeration
  • Over watering, Onset of root disease
  • The pH is too high
  • Too much salt in the water
  • Room temps too high or too low

All of these stop the plant from taking up nutrients in the correct quantities and balance.

Why do plants stretch?

Plants stretch when the light is insufficient or humidity is too high. Lack of ventilation is often the cause of high humidity, or too many plants in a small area. A larger fan may help to fix this.

Why are my plants roots brown?

Healthy roots are white. Brown roots are usually those that have been attacked by disease, probably pythium. Another sign is older leaves dropping off. May be caused by over-watering or bacteria in the water. Can be from tank or tap water. Consider “Microbial” to pre-condition your water.

My plants have very small bugs that spin webs, what are they?

They are known as Red Spider or “Spider Mite”. They can cause severe damage and should be treated by spraying the plants when small to prevent an infestation happening. Mite rid can be used for treatment.

What are the small black flies around the edges of my pots in the coco and around the root system of my plants?

These are Scarid Fly, also known as fungus gnats. They can easily kill a plant if left untreated. Their larvae chew on and devour the fine root hairs of your plants. This damage increases the risk of waterborne diseases such as pythium. Eradicator or Scarid 10 are very effective for the treatment of Scarid Fly. A fungicide should also be used after a Scarid Fly infestation.

What is the brown rotting in the flower buds?

This is nearly always a disease called Botrytis (grey mould). To help prevent this use Silica. If you already have this then Eco fungicide will stop the rot spreading through the flowers.

What are the white powdery spots on the leaves?

This is most likely a disease called Powdery Mildew. This disease spreads by airborne spores that enter the grow tent from the ventilation or when the door is opened. To prevent this, try a bit more ventilation. If you have a severe case of powdery mildew try Eco fungicide.

Is it necessary to aerate the nutrient solution?

Yes, aerating is a good idea as it improves plant health by adding oxygen to the system and protects against stagnant water. With organic nutrients, use a water pump instead of air.

What temperature should my nutrient solution be?


Between 18 - 22°C. If your nutrient solution is too cold use a water heater, if it is too hot use a water chiller.