POND FILTRATION: DO I NEED IT? IF SO WHAT IS THE BEST?

POND HEALTH AND THE TECHNOLOGICAL SAFETY NET: beginners guide to the myriad of filters, biological filters, ultra violet  clarifiers, bubble bead filters, skimmers and protein skimmers etc.

It may be the case that in the creation of the water garden of your dreams, you have had to bend the rules a little on occasion. As a result, your pool water remains green. You may, for instance, have had to build it a little too close to some trees and it catches a lot of leaves blown in by the prevailing winds of Autumn. There may be some other unavoidable pollutants or sediments coming getting in from soil run off etc. The plants may not be getting established quickly enough and you are impatiently waiting to see your fish. Having forked out all that money you dont expect to spend a summer looking at green pea soup. After all you dont spend several hundred quid on a telly, only to sit there with it on, with the brightness and contrast turned down to minimum. 

On the other hand, we go on about the importance of plants in the water to keep the pond clear, but the trouble is by the time the plants are keeping the water clear efficiently the pond is over two thirds covered with plants. It may perhaps be the case that you just dont want to see so much 'water weed' and would rather see more of the action. At the moment it’s like trying to watch 'East Enders' on telly with half a dozen doilies gummed to the screen!

Fish are a major strain on the systems and balances that help keep a pond clear, especially if you feed them. So if you have fish you are very fond of you will inevitably have to contemplate a filtration system. It may be that everything is just right, the population of fish is below the 2 inches of fish per square foot of surface area and the pond is still quite clear - most of the time. But being a slightly insecure sort of soul, you would rest easier in your bed at night knowing there was some further insurance to the quality of the environment for your cherished fish, rather than having to cope with the trammels and trials of the natural world. Besides there is always the prospect of little ones, and what sort of world is it going to be to bring them up in? And then when they all grow up, when things get overcrowded many fish-keepers find it very difficult to get rid of their fish.

So what does technology provide to help in these situations? And how will you know what is the best way of dealing with a particular problem? The solutions are easy but these problems are resolved at no little expense.

RULES you need to abide by to avoid resorting to technology

If your pond has water quality problems or you think there is the potential for problems, get yourself a water testing kit. This will tell you first and foremost the pH of your water. Next in order of importance, the ammonia content, the nitrite content and the nitrate content, oxygen also can be tested for, but your familiarity with the pond and the pH reading can give you an estimate of this. Get used to using the kit and try to be familiar with how the readings should be when things seem to be going swimmingly. Now you are prepared to diagnose any potential problem. However to avoid any problems that may loom up in the future and if they are going to be solved or abated then you must start sticking to some rules.

1.FISH FEEDING. Dont over feed the fish. Only give them as much as they can consume in 5 minutes and net off the rest.

2. OXYGENATION. Nothing is going to work; nothing is going to help the fish unless there is an adequate supply of oxygen. From cloudy polluted water, green water, algae problems, fish gulping at the surface, fish diseases, silting up with organic matter: these are all problems that can be cured with products available from your aquatic store. But none off them will work, be they chemicals, u/v sterilizers or hundreds of pounds worth of filtration units, unless there is enough oxygen about in the water to be used in the chemical processes that break down complex chemicals and organic matter to its basic elementary ingredients.
In fact a lot of the problems that inflict pools and ponds can be held at bay with just a goodly supply of oxygen. This oxygen can come from oxygenating plants under the water or from the air wafting over the pool surface.

But as aquatic retailers will tell you, the season for pump buying starts in earnest with the first hot, still, humid weather. It is then that the colonies of oxygenating plants cannot keep up with the supply of oxygen required for all the pond residents. Indeed they use up the depleted stocks come nightfall for their own respiration needs. So here is your first good reason for turning on the fountain or waterfall. If you haven't got one, get one. Spreading water out and moving it through air, creating as much surface as possible to come in contact with air gives it an opportunity to absorb as much of the essential oxygen as possible.

2. KEEP ON RUNNING. This oxygen is required 24hrs a day, so keep your waterfall or fountain running at night. Apart from the fish needing it to breath, the aerobic bacteria in the bottom of the pond need it to break down the organic matter that is detritus or fish muck. They can only exist for 2hrs or so without oxygen before they die. In order that it gets down there, the whole mass of water needs to be circulating in a gentle cycle. So keep the fountain pump as low as possible in the pond without actually being on the very bottom and move the waterfall pump well away from the waterfall inlet to help circulate the oxygenated water. This may seem contrary to other advice and in certain circumstances it would be unwise like for instance in the dep mid winter and any extreme heat of summer.     

3.Don't keep adding dead, chlorinated, heavily limed tap water to the chemical equation, unless there is an emergency. It only provides another problem to work against. However if an emergency supply of oxygen is required at a moment's notice or an instant partial water change is needed, then a hose running into a pond from a height is the only remedy. The splashing of the water beats oxygen into the pool water and dissipates the chlorine content of the tap water by as much as a half.

4. KEEP THE PLANTS. That two thirds pool cover from all those marginal edging plants, waterlilies and submerged aquatics that act as oxygenators has to be maintained. In fact, make sure there is a healthy population of floating plants in there too. All these together will hoover up the nitrates and phosphates in the pond that would otherwise feed algae.

TECHNOLOGY TO THE RESCUE: Biological filters

If the view of all those plants obscuring your fish is an anathema or the possibility of emergencies seems daunting and you want to have more positive control, then you can have it at your fingertips with a BIOLOGICAL FILTER. This is a ‘TURBO’ version of a pond bottom. It has a biological effect of making the pool larger. They effectively allow you to have the maximum amount of fish in a pool, with less plants and still be able to see them. The same oxygen dependent bacteria live in these filters as live in the bottom of a pond. They are fed a constant stream of oxygenated water along with the detritus and chemicals they are meant to digest and break down.

                      HEADACHE of GREEEN WATER

If you saw your problem as GREEN WATER - it is not. Rather like a headache, it is a symptom of something wrong. It is not the problem itself. One might easily assume that if this were the problem it could easily be cured because the problem seems to be the millions of microscopic free floating plants creating the 'pea soup' effect, the best way to get rid of them would be to kill them or sieve them all out. Removing them is easily done just by mechanical filtration, but unless the thing that is causing the algae to proliferate is stopped,  the algae just keep proliferating and the filter eventually clogs up and needs to be cleaned out. Killing the algae just has the effect of making them rot and turning into plant food that feeds the next generation that returns all too quickly. Those of you who have installed new filters in ponds know that clean filters out can become a daily chore in the summer months as the algae just keeps coming. So it is the stuff that is feeding the algae that has to be removed and this isdissolved within the water. We could mechanically remove the algae to make the water look clear, but it would not be necessarily be free of the compounds that feed the algae. In fact it may not even be safe water for the fish to live in, after all isn't nitric acid perfectly clear?it is not necessarily the case that clear water is safe water.

If for instance you were to do nothing at all, and the algae were allowed to bloom and bloom in a pool with no other plant life to fill the niches in the ecosystem, the algae would eventually all die once resources were depleted, and sink to the bottom and the water would be clear for a while. Meanwhile the algae would rot and become the nutrition for the next colony to bloom and so life would go on. During the rotting phase, the danger of the environment becoming stagnant, devoid of oxygen and unable to sustain life, ever increases. Eventually there could be a build up in ammonia or nitrites that at certain concentrations would kill fish, but the water at times would still be perfectly clear. If however there was oxygen in the water then Nitrobacter and Nitrosomanas, the oxygen dependent bacteria, were introduced, things would change very rapidly.

CURE BY BIOLOGICAL FILTRATION

With a biological filter, you are not only trapping the algae, the bacteria are digesting them as they decompose whilst treating the chemistry of the water, the same breed of aerobic bacteria that would normally be in the bottom of a pond. What is more, this can happen away from the pool environment. Combine this with the innovation of an Ultra Violet Clarifier (UVC); you have a pretty effective solution to your pond water problems.
BUT turn that thing off for more than 2 hours and those friendly bacteria are starved of oxygen, the reverse could be true. It could start producing toxic or nutrition for algae straight back into the pond.
Although the aerobic bacteria are capable of turning ammonia into nitrites and nitrites into nitrates, the filtration process may not be considered complete to the extent that nitrates are broken down. This only happens when colonies of bacteria referred to as ANAEROBIC bacteria build up in the slower moving parts of the filter that break nitrates down into the elements of oxygen and nitrogen. Some manufacturers claim they have incorporated de-nitrifying zones in their filters where the water is processed in a slower, separate filtration area. This is the case with some of the more expensive filters in the Oase Biosys range.

Other fish keeping enthusiasts use an amazing volcanic stone called zeolite, which even in very small quantities removes impurities from water. This is also one of the constituent ingredients in water purifiers used by the extremely committed koi keepers, but here we are getting into the realms of another serious pastime that deserves at least another book. But rest assured, if you plan to take the technological route there is somewhere down that route at some level of expenditure, a solution for your problem.  Otherwise you can keep to the biological route by depending on the larger plant life of the pond to take up the nitrates as fertiliser before the algae can absorb it.

You an take the biological weight of the system, or cover your tracks a bit if you have dug the pond too close to some tree, by incorporating a skimmer. This will remove any debris floating on the surface long before it has a chance to sink to the bottom and rot thereby becoming a biological liability.

Now there is a little bit of a problem with this ideal. Having the bacteria available to break up the nitrates to there constituent parts is not always that easy and even if you had a lot of bacteria that could remove nitrates then some of the plants would not grow very well. This is often the case when people use the product Viresco available from this site, which is a mixture of bacteria that will do this very effectively. One other idea is to establish REED BED SYSTEMS to do this very thing, with special nitrate grabbing plants growing remote from the pond. Here you have your pond water filtering down through a series of troughs full of gravel planted up with these fast growing plants like reeds or watercress. This is highly effective and the principle is even used by water authorities in areas of extremely high organic and chemical pollution and it can be done on a small scale in and around your pond. This will be covered in a following article both on a theoretical and DIY level and will be linked to this article.