Tag Archives: koi carp

Should I Keep Aquatic Plants?

There is a split between pond owners as to whether to have plants or not. Aquatic plants can be a great aesthetic addition to your pond, as well as providing several health benefits to the water and fish. They offer shade, compete with algae, remove harmful nitrogen and give back useful oxygen into the pond.

How To Stop Koi Eating Plants

One reservation some pond keepers have when deciding whether to keep aquatic plants is that some fish, Koi especially, like to eat the plants, upset pots or disturb the soil, resulting in a dirty pond. This can easily be resolved by either planting in aquatic cloth liners or aquatic gravel.

Alternatively, there are some plants that would benefit from being planted in waterfalls or streams, keeping them out of reach for fish, whilst still purifying the water.


Different Varieties Of Aquatic Plants

Water lilies and lotus’ are common floating plants that provide much needed shade for fish. This shade also slows down the growth of any pond algae and sludge as it restricts the amount of sunlight that can reach the algae. As well as providing shade, these plants also compete for nutrients with existing algae. The combination of shade and nutrient competition results in very little algae growth.

Submerged plants such as hornwort and water moss are essential to a well-structured pond or water garden. They provide small fish with cover from predators such as herons and cats. They also provide the water with copious amounts of oxygen whilst absorbing some of the more harmful chemicals in your pond such as ammonia and nitrogen. Be sure to plant these plants in aquatic gravel or cloth liners to avoid fish digging them up.

Shallow water or marginal plants can sit on the shelves of ponds and provide all the health benefits of submerged plants whilst providing shelter and protection for other aquatic wildlife such as frogs, newts and dragonflies. Some varieties such as water iris produce vibrant flowers that add another dimension to your pond throughout the year.


What Are The Ideal Water Parameters For Ponds?

They are often overlooked, but having the correct water parameters is one of the most important factors to a successful, healthy pond. Providing your parameters are correct, your fish will be healthy, aerobic bacteria will be able to thrive and do its job properly and any pond plants that you may have will be able to contribute to the condition of your pond.

Correct Oxygen Levels in Ponds

The maximum amount of dissolved oxygen that can physically be held in water is 18.0mg/L. The minimum that you should let that figure get to is 6.0mg/L, anything lower than this and your fish will start to suffer. Some fish will be able to tolerate lower oxygen levels than this but it is advisable to try and keep the minimum at 6.0mg/L. Cold water can hold almost twice as much oxygen than warm water so keep a close eye on your oxygen levels throughout the summer months.

There are a couple of things you can do to maximise oxygen levels in your pond. Keep plenty of oxygenating plants, install a waterfall as this will bring in oxygen with the water and if needed, install an air stone or fountain to inject further oxygen.

If you need to make a partial water change for something, it is important to test your oxygen levels as tap water naturally has very low levels of oxygen in it.

What Should Pond pH Be?

Ph levels in ponds are very important but first we are going to have a quick chemistry re-cap on what pH is. Ph is a numeric scale that is used to determine the acidity or alkalinity of a substance, in this case pond water. The scale ranges from 1-14 with 7 being neutral, 1 being the most acidic and 14 being the most basic, or highest alkaline level. Battery acid has a pH of 1.0 whilst Lye (used in household drain cleaners) has a pH of 13.5, both can be just as dangerous as the other and give you a good indication as to why keeping a balanced pH level I so important.

Now that we have gone over what pH is, lets cover why it affects your pond, what it should be and how to change your pH level. A fish’s natural pH level is 7.4 so it is best practice to keep your pond as close to this level as possible. Fish can tolerate slight fluctuations in the acidity or alkalinity of the water but only down to about 6.8 and up to 8.2. When testing your pond’s pH level, be sure to test it twice in the same day, once first thing in the morning and once late in the day, preferably evening and preferably during similar weather conditions. The reason for testing twice is the algae that will be lurking in your pond. Algae is only active during daylight hours and when it is active it absorbs large amounts of carbon dioxide found in your pond causing your pH to read high. If your pH level looks a bit too high or low, you need to gradually bring it back down, you can do this by using Pond Equaliser.

It is crucial to keep your pH as neutral as possible. High alkaline levels in the water will increase the toxicity of any ammonia that exists in your pond, leading to possible Ammonia poisoning.

What are KH Levels?

KH is the measure of carbonate hardness in your pond and carbonate hardness is the amount of calcium carbonate in your pond. Calcium carbonates are very important as they feed the nitrifying bacteria that remove harmful ammonia and nitrates from your pond water. These bacteria are part of your ponds bio-filter, without this, your pond would be under great threat and would rely heavily on your mechanical filtration system. KH levels should be around 125ppm but they can fluctuate safely by about 20ppm either way.

Unfortunately, as with low pH levels and low oxygen levels, the effects of low KH levels can’t be seen by eye. You may notice that your ponds condition will deteriorate, Ammonia and Nitrate levels will rise and your pond will become more susceptible to pH swings which will ultimately lead to a pH crash!

Ammonia, Nitrites and Nitrates

Ammonia is released into your pond when your fish excrete waste. The nitrifying bacteria that are fed by calcium carbonate then break down the ammonia and turn it into Nitrite. Nitrite is then broken down further, to its final state, Nitrate. Nitrate is the final by-product of Ammonia. All three of these can be dangerous to your fish and should be monitored carefully. Ideally you should be removing any Ammonia in your pond to avoid it damaging your fish or breaking down further. Ammonia can cause Ammonia poisoning that can lead to death, Nitrites and Nitrates are not as dangerous but if your fish already have Ammonia poisoning they will be weak and susceptible to the irreversible effects of Nitrates.

Ammonia levels should be kept as low as possible, ideally at 0ppm but they can be okay at 0.5ppm if your pH level is neutral. Remember, the higher your pH, the more toxic Ammonia becomes so it is best practice to keep the level low. Likewise, Nitrites should be kept as low as possible around 0.25ppm but ideally at zero. Finally, Nitrate levels should be around 20-60ppm.

To summarise, water parameters are one of the most important things to monitor in your pond and they should be as follows;

Oxygen – Minimum of 6.0mg/Litre

pH – Keep your pH level as neutral as possible, around 7/7.5

KH – Keep your level between 95ppm and 150ppm

Ammonia – Should be at zero but can go up to 0.5ppm depending on the pH level

Nitrite – Like Ammonia, it should be as low as possible

Nitrate – Can be in-between 20 and 60ppm

You can stabilise pH, KH and ammonia levels with Pond Equaliser and stabilise Nitrate levels with Nitrate Klear.

Why Do Ponds Go Green In The Spring?

Ponds turn green in early spring. That’s pretty much gospel among pond keepers; it’s just the way things are.

Why does it happen?

Basically, there are two types of bacteria in a pond – aerobic (good) and anaerobic (bad).  These two types of bacteria are in a constant battle to digest the organic debris that ends up in the pond (twigs, leaves, fish food etc). When the anaerobic (bad) bacteria digests it, it takes a lot longer and produces gases like nitrogen and phosphorus which, in turn, act as a food source for algae. When we add aerobic (good) bacteria to the pond, they overcome to the anaerobic (bad) bacteria and digest the organic debris a lot quicker and don’t create any harmful gases. This is why, when you use bacterial pond treatments you are getting to the source of the problem; rather than just eating the algae, you are starving it of its food source.

The problem is that anaerobic (bad) bacteria can digest organic matter as low as 6°C, whereas aerobic (good) bacteria treatments traditionally work around 10-12°C. This means that all winter your pond is losing the battle against algae and when spring comes, the algae starts to feed.

It’s all about to change

Envii Winter Pond Treatment is a new type of aerobic bacteria treatment.  It works as low as 4°C which means that you can win the battle of the bacteria all year round.  Its task-specific bacteria digest the organic debris meaning that when you come back to pond in spring, it will stay clear. Then continue to treat with Envii Pond Klear and your pond will never go green again!

This is the first pond treatment designed to work all through the winter!

For more information on Envii Winter Pond Treatment, click here. 

Customer Stories – Adrian Rodgers

Here’s a great review we recieved about Pond Klear from Amazon Customer, Adrian Rodgers –

“For as many years as I can recall our well stocked fish pond has turned green in spring and we haven’t seen a fish until almost autumn. We’ve tried plants (much to the delight of our grass carp), as many chemical remedies to reduce the algae bloom as there are on the market and traditional barley hay. It’s safe to say that we have never known what eventually gets on top of the problem, it just clears one day.

This year however is different. We introduced your product in early April during which, luckily for us, there was a really cold spell which, presumably delayed the onset of our annual algal bloom problem. Your product states that it works at cold temperatures but nevertheless given our 10 year experience of green water and the multiple products used I must say not much success was anticipated. I’m delighted to state that I was completely wrong. I followed up with a second dose a week later and at about 1 month from dose 1 I’ve added a third. We’re now mid May and the pond is delightfully clear despite the warmer weather and long daylight hours. We no longer have to wait until feeding time for a glimpse of a fish mouth!

Further, the slurry I remove from the filter box no longer sends a whiffy bad eggs aroma up my nose when I lift the lid and I suppose this is a further effect of your product.

An excellent product which I will buy again.


Adrian Rodgers, delighted customer.”

Click here to buy Envii Pond Klear 

The perfect storm in your pond

Last month we wrote an article for Koi Carp Magazine. Here it is –


This winter has been warm! The average temperature in December was a balmy 8°C and January wasn’t much colder. Plants are blooming months earlier than they should and insects don’t know whether to hibernate or pollinate.. It’s almost as though the difference between the seasons are becoming indistinguishable. But what effect will this have on our pond’s biological balance when the ‘real’ spring arrives?

Let’s start from the top. Your pond is naturally full of organic matter. Whether it’s the twigs from overhanging trees, droppings from an unwelcome pigeon or your beloved koi’s own bodily functions, every pond is full of organic material that will decay. This process of decay introduces substances such as phosphorous, ammonia and hydrogen sulphide into the pond water. Small amounts are fine, in fact they’re normal, but too much and they can easily affect water quality and the health of your fish. We call this the “organic loading” of a pond. The more organics, the more decay, the more adverse effects on water quality.

This is the essence of most pond water problems. If the pond’s biological balance is out of kilter, you open the door for excessive amounts of ammonia, nitrites, nitrates, phosphates, urea, faecal matter and dead organic waste. Therefore most owners use various pond treatments tackle this issue by introducing task-specific ‘good’ bacteria into the pond environment.

The reduction in these contaminants improves the quality of the water and that combats a wide range of aquatic pathogens and diseases such as: streptococcus, pseudomonas, aeromonas, vibrio and burkholderia. In essence ‘good’ bacteria tackle the ‘bad’ bacteria that are effectively feeding off the organic matter in the pond.

But surely a warm, mild winter is good for us and there will be less adverse effects in Spring?

This is where the answer gets a little muddy (pun very much intended). Organic matter decays as low as 6-7°C, which means in the very cold weeks of the year, the pond becomes almost dormant and you can almost leave it alone. However, this winter has been very different. As I said before, the average temperature for December was 8°C… an ideal temperature for organic matter to decay without any competition creating sludge that builds up into an anaerobic environment to emit toxic gases such as hydrogen sulphide.

To add insult to injury, this winter’s been one of the wettest (and probably windiest) on record as well. Gale force winds have distributed a veritable smorgasbord of organic detritus around our gardens and some of it will have inevitably found a home in your pond.  High levels of rainwater, which is packed full of nutrients such as sulphur (think acid rain) and minerals provides a readily available (and this year plentiful) supply of nutrients to help organic matter decay. Consider how much better your plants grow when fed with rain rather than tap water! Or how when you collect rainwater in a water butt, invariably there will be a layer of algae over the top. The ‘bad’ bacteria in the pond thrive off this free buffet of nutrients, which only speeds up the decaying process and helps generate sludge.

So we have in essence the makings of a ‘perfect storm’. Lots of organics and nutrients being added to the pond, mild temperatures of around 8°C aiding decay and the fact that almost all traditional pond treatments are only effective from above 10-12°C.




This is why you can expect to see some real problems when spring eventually starts.

There are a few tried and tested methods of reducing the impact of green water, sludge and other algae problems in spring –

  • Physically removing as much sludge and organic matter from your pond – You can do this with a net, bucket or even with your bare hands but it’s not always practical.
  • Keep your filters clean – so you can catch as much organics in the water column as possible
  • Add plants – In a natural pond, plants will absorb a lot of the bad nutrients, but they can’t cure the issue and too many and you can’t see your fish!
  • Add plenty of task specific bacteria at the start of spring – Providing the bacteria in question is safe in large amounts, add a double or triple dose for the first few times in spring. Bacteria grow logarithmically – 1 becomes 2, 2 becomes 4, 4 becomes 8 – so the more you add the quicker the results.
  • Avoid adding any materials that can act as a nutrient to the ‘bad’ bacteria – with the high organic loadings the last thing you want to do is add a nutrient.

Have pond treatments kept up with our evolving climate?

Bacteria can be genetically modified (although there are ethical and moral question marks with this) but it’s far more common that new strains are discovered in natural occurring environments. In many ways it’s a game of chance, thousands of strains can be examined without finding anything that can improve on the strains you already have. This means that when a new strain is discovered it can be a big deal.

In late 2013, a strain of bacteria was sampled in a stream in Pennsylvania. Like many others it was catalogued and its characteristics examined and it showed signs of very good activity at low temperatures. In fact, it showed the same activity at 4°C as similar bacteria do at 10-12°C. It was so unique that the unusual step was taken to patent it!

Its natural environment was in water which made it incredibly suited for water treatments and was very active in breaking down organic waste, therefore just what you would want in a bacterial based pond water treatment.

This activity means that it’s food source are the same organics that create problems in your ponds and also provides a stable and continued treatment even during temperature spikes. Why you may ask is this important? Well imagine going for a run. It’s much easier to run for longer and with less effort if you keep a rhythm, rather than stopping at traffic lights, crossing the road or opening a gate to a field. Well, it’s the same principle for bacteria – In spring we see periods of really warm weather (24°C on one day in May 2015) which raises the water temperature in our ponds above the 10-12°C allowing traditional bacterial strains to become active, but periods of cold weather stops any activity. In fact the mean averages in the UK last year were; March – 5.5°C, April – 7.9°C and May – 9.6°C!. For the best bacterial activity you want the bacteria to concentrate on digesting organic matter rather than wasting energy stopping and starting due to temperature fluctuations, as they become much less effective.


Thermometre graphic


These new low temperature strains look to be the ideal answer as they provide you the pond owner with more constant and reliable bacterial activity much later into the year, and arguably more importantly much earlier in the year to tackle the inevitable build-up of organic matter that the warmer and wetter winters are bringing.

Bio8 Ltd exclusively manufacture the new Envii Pond Range which incorporates unique patent pending bacterial strains that are fully active at temperatures as low as 4°C and more information can be found at www.bio8.co.uk or contacting them directly on 01246 240880.