Solving New Pond Syndrome / New Filter Syndrome in newly installed garden or koi ponds

Question:
I have just finished building my pond and before I start adding Koi I want to get a few things clarified that have been worrying me, such as New Pond Syndrome. Will my pond suffer from this? Do all new ponds suffer? And is this roughly the same as New Filter Syndrome? Is there anything I can do to protect my pond and fish? What steps, if any, should I take before adding Koi to my pond?

Answer:
Your research into new pond syndrome is already paying dividends, as it’s making you cautious before you even consider stocking your pond with koi – and rightly so. New Pond Syndrome is often the first (and most expensive) problem encountered by new pond keepers and experience it at the expense of the health of their koi. In some cases, it can seem so extreme or final with solutions seeming so long term and costly, that NPS can put people off keeping koi altogether. Many first encounter it unknowingly in the form of diseased fish appearing, hoping to medicate the problem away. In fact where NPS is the cause of health problems, treating fish will not solve the problem.

Fortunately, with a little preparation, and cautious progress during stocking of your pond, you should be able to save both yourself and your koi from a catalogue of problems.

Will my pond suffer from NPS?
The vast majority of ponds (and aquaria) will experience NPS to some degree. This phenomenon that you are concerned with is caused by an accumulation of toxic waste excreted by your fish in a new pond and filter set-up. Perhaps a more accurate description would be to call it New Filter Syndrome as the water quality deteriorates as a result of a filter (rather than the pond) not being sufficiently mature to process the waste that your koi produce. Furthermore, a new filter upgrade on even the most mature of ponds would lead to the same water quality problems.

New Pond Syndrome is a technical way of describing what can happen if a new pond is stocked in haste. We’re used to getting fast food on demand, or coffee in an instant and could well be forgiven for expecting an ‘instant’ pond could be achievable. You will have spent a healthy sum on the best filtration for your pond, having researched how well suited it is to your pond’s requirements, safe in the knowledge that it will filter your pond effectively – but stop! There isn’t such a thing as instant filtration and it is those pond keepers who are non-the-wiser that are the ones who will unfortunately experience NPS.

As soon as a new pond is stocked with fish, a continuous ‘trickle’ of ammonia is released into the water. As the trickle continues, the concentration of ammonia starts to rise causing the pond’s water quality to become dangerous for its inhabitants.

New ponds are relatively lifeless. Constructed out of inert materials, and filled with water that has been disinfected to make it suitable for drinking, compared to a natural water body, a new pond environment is relatively dead.

Unfortunately, it is the abundance and diversity of microscopic life that processes and detoxifies ammonia (and other pollutants), preventing them from accumulating. Any stable water body (whether natural or artificial) depends on a thriving population of bacteria and protozoa to keep them ‘sweet’. Different bacteria process different types of waste, passing semi-processed waste down the line for other bacteria to process further. The rate at which your pond can handle fish waste is therefore determined by the density and diversity of bacteria in your filter. If the population is not sufficient compared to the level of work demanded of them, then we experience an imbalance and build up of pollutants and this in essence is New Pond Syndrome.

Do all ponds suffer from NPS?

All new ponds have the potential of turning toxic if they are not stocked and run-in with care. The larger the pond, the better the chances of a pond not experiencing extreme case of NPS – purely on the basis of dilution. But even if the diluting effects of a large pond can off-set the harsh realities of NPS, its filter will still need to mature so that when the large pond is adequately stocked, it can handle the waste produced by the koi. The maturation process will still prove to be a lengthy process as the different bacteria colonise, multiply and process the various forms of waste that will start to accumulate within a pond. In fact, if the levels of ammonia in a new pond are too low, then this will limit the population of bacteria that can be sustained in a filter, limiting its rate of maturation.

By maturation, we mean a filter’s ability to process the ammonia and associated by-products at the same rate that they are being produced in a fully stocked pond.

Is there anything I can do to protect my pond and fish?

The best thing you can do to protect your fish is to understand the risks of NPS, how it occurs and how you can minimise it’s impact on your fish.

How NPS occurs.

A useful way of visualising what is happening in your pond and filter is to imagine three barrels, each fitted with a tap. Barrel No.1 collects ammonia from your koi, barrel No.2 collects nitrite from Barrel No.1 and Barrel No.3 collects nitrate which is fed to it by Barrel No.2 (see Figure 1).

In a pond that is suffering from NPS, either barrels 1 + 2 will be filling up quicker than the taps allow them to empty. This will be clear by testing your water for ammonia and nitrite. The results will tell you where you are getting the bottleneck and which parts of your filtration are not coping. For example, if the ammonia is high, then the ammonia-converting bacteria will not be processing sufficient ammonia. Likewise, if you have a high nitrite, then your nitrite-converting bacteria are also in an immature state. In extreme cases, you could also get high readings for both ammonia and nitrite. However the more mature your filter, the bigger the tap, allowing more waste to be processed. Ultimately, in a mature and balanced koi pond, the tap’s capacity in barrels 1 and 2 will be far greater than the rate at which ammonia and nitrite are produced in the system and hence ammonia and nitrite levels will always be zero.

What steps should I take before adding koi to my pond?

1. The most reliable method of preventing NPS is to stock your pond wisely and patiently. This will mean adding fish only a couple at a time, monitoring ammonia and nitrite levels, observing and recording levels so you can satisfy yourself that the filter is coping with its new workload.
2. Help the maturation (open up the barrel taps) of your new pond and filter system by adding a source of bacteria. The more diverse and larger the bacterial population that your filter can sustain, the quicker they can process the waste, passing it on to the next barrel. Traditionally this has been a waiting game, waiting for Mother Nature to colonise the filters naturally (and slowly). However, filter boosters can now be added to speed up the process, or the addition of some mature filter media (or filter extract) from a fellow koi keeper whose pond you trust has been free from problems and disease. This will provide your filter with high levels of ammonia and nitrite loving bacteria straight away, rather than waiting for them to arrive naturally.

How do I stock the pond without risking NPS?

As soon as an new pond is stocked with koi, a continuous trickle of ammonia is released into the water (filling up barrel No.1). As the tap is virtually closed at this stage on account of there being very little bacterial activity, the ammonia barrel will start to fill up. You can reduce the amount of ammonia that your koi produce by stopping feeding immediately. You should also reduce the ammonia level by carrying out a partial water change with treated tap water, diluting the toxin away. However you must be in a position to start feeding them again soon, so you need to look at a way of opening up the taps so your filter can handle all of the ammonia that it receives.

What if I get an ammonia or nitrite reading during stocking?

It is highly unlikely that you will be able to mature your filter and stock your pond without experiencing an ammonia or nitrite reading, so be prepared to accept low levels. However, should either rise significantly you will need to react quickly.

1. Carry out a partial water change
By carrying out a partial water change, the lethal levels of ammonia (and/or nitrite) can be reduced but not removed completely, allowing the bacteria population to increase as they continue to break down the residual levels of ammonia. The nitrite peak can also be diluted, but again, not totally removed so as to deny the bacteria a chance to mature, but at the same time to a safe limit for the fish.

2. Stop Feeding
As ammonia excretion is related to the level of protein in the diet, fish should not be fed while there is a positive ammonia reading. In addition, should the first partial water change not reduce ammonia levels below acceptable levels, then a further water change would be necessary.

3. Proceed with caution
Subsequent stocking should only be continued when ammonia and nitrite levels have been at zero for a week, and then additions of new stock limited to 30% of existing stock. For example, if you have 12 koi, stock 4 additional ones at the most. Continue to test for ammonia and nitrite and ensure that the filter manages to handle the increased stock, intervening with water changes and reduction in food if required (as highlighted by your water test results).

With adequate care and attention, this initial maturing phase should take 2-3 months before you can be a little more relaxed with stocking and feeding. The test of a fully matured filter is that it will handle a high ammonia output from your fully stocked pond with no trace of ammonia or nitrite being present in your pond.

How to prevent NPS in 10 easy steps

1. Understand that the cause of NPS is effectively an overburdened immature filter.
2. Add a diverse source of bacteria to your new filter from either an off-the-shelf bacterial filter start or some mature media from a reliable koi keeping contact.
3. Buy accurate ammonia, nitrite and nitrate test kits.
4. Add koi gradually, aiming to have your pond fully stocked no sooner than in 3 months time.
5. Feed sparingly, being aware that food is the major burden on your new filter
6. Test the water frequently to ensure that ammonia and nitrite levels are acceptable.
7. Keep a log of your test results and track how your filter copes with more fish and food.
8. Carry out a partial water change and stop feeding as required if ammonia and/or nitrite levels rise too high.
9. 6 weeks after adding your first fish, check that the filter can process any rise in ammonia/nitrite in under 1 day. If it can’t, go back to step No.8.
10. Once your pond is fully stocked, confirm that your filter is now mature enough to cope by putting it through a heavy feeding regime and confirming that all subsequent ammonia and nitrite is rapidly processed by your filter.

What are the signs of NPS?

Fish excrete ammonia because it is toxic. Consequently, by excreting it into the pond water, the whole pond environment inevitably turns toxic (unless it is broken down at the same rate by bacteria). Typical ammonia intoxication symptoms are gasping at the surface, lethargic behaviour, and excess mucus secretion. If fish have managed to survive the surge in ammonia, then they will also have to overcome the associated nitrite peak. Nitrite behaves differently from ammonia in several ways. Firstly, compared to ammonia, nitrite is far more persistent having built up in a new pond. Where ammonia levels may have dropped quite rapidly once Nitrosomonas bacteria had kicked in, with nitrite, it takes Nitrobacter much longer to process this stubborn pollutant. In extreme cases, nitrite levels can accumulate to such high concentrations that they even inhibit the beneficial action of those bacteria that break it down. An accumulation of nitrite in the pond causes nitrite to accumulate in their blood as they indiscriminately absorb through their gills. This reduces the oxygen carrying capacity of their blood, causing koi to gasp, flash or scratch through irritation.