pH Control

PEST CONTROL

The power of hydrogen or, pH. pH ranges from zero being battery acid to… The other end of the scale Liquid Drain Cleaner, at pH 1 4. Pure water has a pH of 7, 7 is neutral on the pH scale. Queensland tap water ranges from 7.3 to 7.7

Plants, fish, minerals and bacteria have different pH ranges within which they operate best. Fish are happy within a pH range of 6.5 to 8. Plants grow in a pH range of 5 to 7.2. What makes Aquaponics work is the conversion of ammonia created by the fish to nitrate, Nitrate is food for the plants. This process is called the NITROGEN CYCLE.

Correct functioning of the NITROGEN CYCLE IS DETERMINED BY pH. It's all done with two oxidising bacteria:

Nitrosomonas which oxidises Ammonia into Nitrite…

Nitrobacter which oxidises Nitrite, into Nitrate, plants uptake the NItrate.

Nitrogen Cycle complete.

Below pH 6, Nitrosomonas bacteria’s ability to oxidise ammonia diminishes. Should pH drop low enough, Nitrosomonas Bacteria STOPS working. Breaking nitrogen cycle, will harm fish and stop the plants from growing. Bacteria enjoy operating within pH range 6 to 8

Plants need the full range of minerals to flourish. pH levels determine if a plant can uptake the mineral or not. Looking closer at iron from ph 4 to 6.3 PLANT CAN UP TAKE as much as it needs. From pH 6.3 upward as the pH increases the plant's ability to absorb IRON diminishes to almost nothing.

The minerals all Aquaponics systems have trouble with are:

• Potassium [Ar]4s¹,

• Calcium [Ar]4s²

• Iron [Ar]3d⁶4s².

If pH drops to low. uptake of potassium and calcium diminish

If pH goes to high, iron deficiency occurs

Looking the full list of minerals... The Range that benefits all mineral uptake is pH 6 to 7

The Target pH level for Victoria Hortus Flexible Aquaponics Systems is 6.8. However a system can function between 6.2 and 7, the optima performance is achieved at a pH of 6.8.

Changing pH radically creates pH shock and Event, fish don’t like. Therefore HC Mk1 Systems have a lot of sumps, to increase the total water volume of the system.

Large bodies of water are hard to heat up and cool down, this stabilises the temperature.

Large bodies of water react slowly to pH changes, reducing the opportunity for pH spike.

The constantly revolving Nitrogen Cycle, produces Nitric Acid as a byproduct! In Aquaponic systems this byproduct forces the pH down.

Potassium carbonate alkaline inorganic compound, a white salt, which is soluble in water, increase pH and also adds Potassium. Potassium carbonate is mainly used in the production of soap and is also used as a buffering agent in the production of wine. To bring the pH up, 40 grams of Potassium Bicarbonate achieves an approximate increase of 0.2 pH and adds potassium to the system

Hydrated Lime… Hydrated lime is a dry, colorless crystalline powder manufactured by treating calcium oxide with water. Calcium oxide is usually made from limestone or seashells, that contain calcium carbonate. Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not enough. Hydrated lime is also used to raise the pH of acidic soils.

30g of Hydrated lime will increase pH by approximately .2 and add calcium to the system.

Hydrochloric acid is the water-based, or aqueous, solution of hydrogen chloride gas. It is also the main component of gastric acid, an acid produced naturally in the human stomach to help digest food. Depending on quality, Hydrochloric Acid has a pH ranging between 1.5 to 3.5. 50ml of Hydrochloric Acid reduces 0.2 pH by approximately

.02 pH may seem small, to prevent pH shock all adjustments must be made small and tested next day. If large changes need to be made, say from 5.5pH to 6.8pH, adding 0.2 every 3 days prevents pH shock and allows the system to return to normal without breaking the biology. Consider this 6.8 is not 7 or 6.6, most adjustments are small

This is the fish tank. Never add any substance other than fish food. The hydrochloric acid or the potassium bicarbonate will create a cloud inside the tank, the fish will swim through. This will harm the fish and most likely kill them. When either increasing or decreasing pH, add the potassium bicarbonate or the hydrochloric acid to the sand bed! The sand acts as a buffer to reduce the opportunity for pH Shock.

We need to be mindful, pH has a global effect over the entire biology of the system.

fish

plant

Bacteria

Mineral uptake

From pH tests you will discover either to increase or a decrease in pH. As always Samples are taken always from the Primary Sump and preferably at the same time of day.