Trouble shooting  filters

But you've got a filter and its got problems. The problems are generally as a result of the original reason for resorting to a filter rearing its ugly head again.

On the other hand they might not be. A process of elimination must be followed - read on....

Filter problems

1.Not working and has never been effective at keeping water clear

a) Have you got the right parameters or filter specifications and is it set up right ?

b) In order to process all the water effectively the pump must be situated as far away from the filter as possible. This situation changes in the depths of winter for other reasons.

c) The filter must be in operation 24hours a day to be effective as a biological filter. What we have done in installing a filter is effectively creating a 'turbo-pool bottom'. If we are hoping to establish the bacteria that thrive an the bottoms of pools digesting dead algae and detritus, then we need to supply them with oxygen constantly. This is obtained from the persistent supply of water from the pool through the filter. This takes about a month to 2 months in good ambient weather conditions to really get established. Or, it can be encouraged with special 'starter' chemicals or a small amount of filter medium borrowed from a neighbour's successful filter.

Fish are also effective at priming the system, effectively fertilising the system with their excrement.

d) Hopefully you have not been regularly topping up with fresh chlorinated tap water, as this will provide minerals for the sustenance of algae and inhibit bacterial growth.

e) Nor have you been cleaning out the filter and filter medium with fresh tap water? This puts it back to day one with regard to its effectiveness and kills the bacteria doing all the great work.

f) If the pump to the filter has a pre-filter i.e. a sponge or a mesh over the inlet, it may be so fine that it is preventing enough of the water borne matter from reaching the filter box itself and so preventing it from doing its job. If cleaning the pre-filter is a continual chore then get rid of it. If it is essential for the performance of the pump then a more robust pump capable of delivering mucky water and suspended solids must be used.

2. The filter gets really dirty and clogs up really quickly- and still not keeping the water clear

a) If the filter has been recently installed, when it is merely operating as a mechanical filter, it is bound to get really dirty. This will slow down the establishment of the correct bacteria, allowing pockets of anaerobic bacteria to get established, which do not do any good if they get established too early and then get hold of organic matter first before the aerobic bacteria. In metabolising the organic matter they can produce methane, which is a poison to the pool environment.

b) When flushing out the filter to increase its efficiency, do not clean out too much of the muck and do not be tempted to use chlorinated tap water to flush it through. This will wipe out the bacteria.

c) If the filter is really dirty you have probably found that the pump is also getting clogged up. Check that it has been delivering the correct quantity of water to the filter to make it effective. See how long it takes to fill up a 1 or 2 gallon bucket with water.

d) Particularly in the early establishment of a filter you might find that there is too much muck in the bottom of the pond for the pond and filter to cope with, therefore it would be advisable to raise the pump up from the bottom temporarily.

e) Is there enough oxygen in the pond to keep your filter alive?

If the water does not seem to be half full of oxygenators then a fountain, waterfall or venturi is necessary to oxygenate the water supply to keep the filter going.

f) Have you been using any chemical treatments? From algicide through pesticides to pond salt - none of them are any benefit to filter systems and even at prescribed doses, are detrimental.

3. THE FILTER DID WORK EFFECTIVELY FOR A WHILE BUT NOW GETS

REALLY DIRTY AND CLOGS UP REALLY QUICKLY. IT NO LONGER KEEPS THE WATER CLEAR.

a) Is there enough oxygen in the pond to keep your filter alive?

b) Have you been using any chemical treatments

c) The reasons that may have stimulated you to fitting the filter system in the first place are still there, have returned and are worse ( The horror movie starts again on exactly the same lines. Its like "Friday 13th Part 4").

Koi carp in feeding frenzy. Overcrowding of fish stock, over feeding and the resultant stress are the commonest causes of water problems and then ultimately disease in fish.

Overcrowding of fish stock, stress and over feeding are the commonest causes of pond water problems from a management point of view. These are not helped by inherent inadequacies of the design of the pool - large shallow areas where the water gets too warm, pollutants and water run-off makes its way into the pond. Also having shade and complex shape does not help.

Perhaps the filter's performance may be enhanced with 'add-on' extras like u/v clarifiers or magnets (see below). These may buy you some more time before you really have to sort the problem out.

d) It may be too cold. Below 10c the filter is no longer operating biologically, i.e. the bacteria in the medium does not break down organic matter below this temperature and so the detritus just builds up. Circulating very cold water in a pond is probably not a very good idea anyway particularly as the temperatures drop towards 4c. Therefore it would wise to thoroughly clean the filter out and put to rest for the remainder of the winter.

Shallow areas, lack or water plants, the potential for run off from surrounding soil, the stream too long and large for the size of pool would make this a very difficult water feature to sustain without regular use of chemicals OR (but not as well as) a highly efficient biological filter system.

4.POOL CLEAR BUT AMMONIA OR NITRITE LEVELS STILL HIGH.

FISH UNDER STRESS AND GASPING AT THE SURFACE.

The biological filter may operating efficiently, mechanically - but the effective breakdown of the chemicals in the water by the filter microbes is ineffective. This would mean that the bacteria are not established enough to be effective for any of the above reasons OR:

a. The filter is over supplied with water and has not enough time to process it adequately.

b. A sudden change or shock to the environment by outside environmental pressures e.g. herons, weather, fertilisers etc. cause sudden increases in metabolism in the fish which the filter cannot initially cope with.

Emergency Treatment:- partial water change of between one third and a half of the water. Beware, if you partially empty the pool and the toxins are still building up in the pool, then there is a danger of them concentrating even further.

1. Run fresh water in from a height so that oxygen can be pushed in and any chlorine in the water (if it is tap water) can be dissipated and just let the pool overflow. It is less of a shock to the fish. To estimate how much water you have actually changed, do a rough calculation on the gallonage per minute by squirting the hose into a 2 gallon bucket. From that you can extrapolate a time to fill half the gallonage of the pool.

Remember to 'condition' the water being on the generous side with the dosage.

2. A tonic dosage of salt will reduce the effects of the toxins but it wont do the filter much good. If you are using Zoolite as a filter medium this will make the situation worse.

5.POOL CLEAR, NITRATES HIGH.

1. Fertilisers and pollutants may be leaching in from the rockery or lawn surround.

2. Apart from outside environmental pressures, this may mean that although the filter is working more than adequately even as a biological filter, you may need a further extension of it. The plant material in the pond is not large enough and capable of using up the nitrates that emerge from the broken down ammonia and nitrites. So therefore you need to establish an extra process of filtration in which anaerobic bacteria break down the nitrates into nitrogen and oxygen. This would normally occur in the bottom of the pond but it may so polished and pristine that a bug would not even be seen dead there!

The clarity is unsustainable in this situation, as any algae will quickly take advantage of the nitrates and bloom. Blanket weed may however be the dominant algae and be taking advantage and helping sustain the water clarity.

Emergency Treatment:- Partial water change. see above.

Consider planted filter bed system, or anaerobic filtration