Advice please - Rain water harvesting for ponds

[bob1]

Hi all, my first post

I am planning a new pond and decided to set up a rain water harvesting system for filling and topping up as well as general garden watering. Seemed like a good idea at the time….

I have two closed IBC 1000 litre tanks connected together which collect the water from the gutters on the metal workshop roof. (Some trees above though).
Both containers were full after a month or so and all looked good. Recently though - late summer before the leaves started falling - I noticed the water had gone a dark colour and smelled stagnant.
After some thought I installed a circulation pump and a UV pumping from one tank through the UV into the other tank and back via a 2” permanent syphon. This works fine flow wise but after six weeks there is no change to the water.

I spoke to my local pond emporium yesterday and they told me that I shouldn’t store or use rain water for pond use. This is because rain water is too soft and minerals are required to be in the water to stabilise the PH and for general fish health. Also stored water is bad because of bacteria growth and the UV will not help kill these types of bacteria. Also I shouldn’t even use the water for watering vegetables and flowers because I will use a spray and this will release legionella into the air which is dangerous. Their advice is to use tap water and add chemicals to remove move the chlorine.

So - my question(s),
is any/all of this true?
Are they just trying to sell me chemicals?
Should I abandon my water saving idea?

I feel rather fed up now after the work and expense of the water harvesting system. Thought I was doing good, but perhaps I should have researched this more before I started.

The planned pond will be 2.4M x 1.8M with about 400mm above ground and 900mm dug out. Planning ornamental sort of thing with some planting and a few goldfish etc. No Koi.

Any comments or ideas welcome.

Thanks for reading

 

[j.w]

@bob1
The only rain water my pond gets is what falls from the sky or what's from our well when it needs topping off due to evaporation. Some here use it from off their roofs etc. Maybe they will be of more help.

 

[JRS]

Welcome to the forum. I let roof water drain into my pond but I do not store it. I have very hard water and the rain water helps counteract that, especially after a lot of evaporation.

Lots of folks in my area use rain barrels; have not heard anything much about Legionella although warm temps appear to be a contributing cause in addition to stagnation. Looks like there is a possibility but depends how careful you want to be and take steps to mitigate the risk.

Lots of different bacteria and pathogens associated with water. I even suspect I may have had a mycobacterium infection in a finger cut after squeezing an aquarium filter sponge to clean it. Culture was inconclusive but the appropriate antibiotic finally killed it. Now I make sure to wear gloves just in case.

Legionella risk in your garden - should you be worried?

Can gardening equipment harbour Legionella i.e compost, waterbutts, hosepipes? and how can you reduce the risk of Legionella in your garden?

www.waterhygienecentre.com

How To Clean A Rain Barrel

www.aquabarrel.com

How Legionella Spreads

These bacteria spread through water systems and devices.

www.cdc.gov