Do not under-estimate the
need for post harvest clean-up.
Failure to do this properly can result in ongoing problems from disease,
plumbing blockages and broken pumps.
separate precautions should be taken to ensure hardware is clean prior to
At the end
of each crop it is necessary to sterilize the entire system to help
prevent disease problems in the next crop.
Step 1. Remove plants and medium from
the system then do as much manual cleaning as possible. External
cleanliness of the system and growing area is as important as internal.
Step 2. Partly fill the reservoir with
water. Lower the water’s pH to between 4.5 and 5.5. Then, after providing
good ventilation for the area and subdued light conditions, add household
chlorine bleach** (50g/L chlorine) at ~5ml per litre (4 tsp per Gal).
Step 3. Mix well, then soak system for
24 – 72 hours. While the system is soaking:
Recirculating systems: Run the pump for at least 15 minute cycles every
Run-to-waste systems: Run the pump for a short burst once every hour^.
Step 4. Discard this solution then
flush the whole system several times with small volumes*** of fresh water
to remove all traces of chlorine and dislodged material.
^ Note that there must be adequate ‘contact’
time (e.g. minimum of 24 hours) between the chlorine and all surfaces e.g.
system sidewalls, pipes, etc. Pay particular attention to areas where
there is usually zero water flow, such as dead-spaces in taps. ‘Flooding’
may be necessary to contact hidden surfaces e.g. underneath the upper
surface of channels.
Also, note that chlorine bleach will not
dissolve algae or general solid material. Only wet brushing will remove
small volumes are more effective than a single flush.
Step 5. Where fine
sprayers are used, it may be necessary to individually dismantle and clean
details on how to remove salt precipitates
(build-up) from hydroponic systems click here
Avoid contact with metal parts and ensure to follow necessary safety
precautions. Use protective clothing (e.g. mask, goggles, gloves).