When building a new pond you need to give it time to establish itself, this is called “cycling” it usually takes a month or so, but a pond could take years to become fully established with plants and fish.
If you’re not going to have fish in your pond you don’t have to worry too much about your pond doing a complete nitrogen cycle, but if you want to have fish in your pond it’s something you need to keep an eye on.
Your ponds ecosystem needs time to establish, it’s very delicate but with time you should have a wonderful pond thats friendly to fish, wildlife and plants.
How Soon can you Add Fish to a New Pond
When you build a new pond you need to fill it with water, this is usually done using tap water, tap water contains chlorine or chloramines which is fatal for fish.
You can add a de-chlorinating treatment to speed the process up, but we would suggest you wait at least 72 hours for the chlorine to gas off before adding fish to a new pond, this will allow the chemistry and temperature to level out, you need to test the water quality weekly to start with.
Do not add too many fish to start with, this will help your pond and your fish, when adding fish leave them in the bag they came in and place the bag into the pond for about 15 minutes so the water to can equalize to the pond water.
If you really want to make sure it’s safe to add fish to new pond you should leave it until there is a good level of beneficial bacteria in your filter system, typically this could take about 30 days.
Establish Beneficial Bacteria
You need this beneficial bacteria to break down organic matter that is present in all ponds.
Fish produce waste (poo) which creates ammonia, bacteria breaks the ammonia down, adding to many fish to start with will overwhelm the bacteria, but a small amount, one or two fish to start with should be ok.
Adding fish could also help keep the filter bacteria alive by feeding them with their waste and not starving them, but dont overfeed them as this can cause excess food waste.
Test the water
As your pond establishes itself you need to test the water, you can use a test kit to get a reading
pH your’re looking for a pH level of between 6.5 – 9, 7.5 is perfect, but as long as it doesn’t fluctuate to much you shouldn’t have problems.
Ammonia levels should be as low as possible ideally 0-1 parts per million.
Nitrate should be lower than 5 per million, the lower the better.
Chlorine should be 0.
You need oxygen in your pond for your fish to breathe and to feed the beneficial bacteria, this happens naturally, but you can add aeration with air stones and water features like fountains and waterfalls.
Plants are another way to establish a pond, they also offer structure and shade to your pond and feed on the nitrates that the beneficial bacteria produce.