Concrete Pond Construction

Frequently asked questions about Miscellaneous

Q. Being very new to keeping fish but 'hooked' already I have recently installed a new pond in my garden. I have since had a complaint from one neighbour about the noise level (running water). I myself along with other people I have asked do not believe there is a problem.... however I am just wondering if anyone else has ever had to deal with the same issue? or does anyone know where i stand legally?

A. With modern housing being quite close together and with smaller gardens complaints of water noise is quite common especially in the summer months when peope have their windows open at night.
It should be quite easy to reduce the noise though.
The most common cause of water noise is a waterfall, but with the colder weather now this should be shut off anyway.
Even a drop of 3 or 4 inches back into a pond can make quite a noise. You can reduce the noise by reducing the flow to the waterfall or altering the fall back into the pond.
Other water noise can be caused by returns from the pump dropping into the pond. If you have a venturi then the return will be underwater and should not make a noise.
If the pump return is above water then you can add a pipe that takes the return below the water surface. Returns from a Trickle Tower or similar appliance can also be dealt with this way and will be completely quiet.

Q. I would like to incorporate an area in the raised wall design for planting reeds and lilies. This will be along one wall and be separated from the main pond by a partition wall. This will provide additional removal of water impurities and provide shade for the fish. Water from the main pond will flow in and out but the fish will not be able to access the area and plants and disrupt the plants and cloud the water.
I have been told this is not a good idea as plants will encourage additional parasites etc and may well cause unnecessary danger to the fish. My current fish include 6 large 12" to 18" Koi , live in a well planted pond which they are outgrowing - hence the need for new pond.
Is this idea sensible or am I creating an unnecessary health risk for the Koi?

A. Quite a few people like to do this and I don't see a problem if you take a few precautions. What you are doing is adding a vegetable filter and this is good for the removal of nitrates. Many people plant watercress in a filter bay for this reason.
However, if you have the main pond water flowing through it, then it is a good idea to have a by-pass so that you can have the water returning to the pond without going through the plant area. This is necessary because you may need to dose your pond with salt or chemicals that would kill or seriously set back the growth of the plants.
Wildlife will visit the plants and there is a small chance that parasites will affect the pond, but this can also happen with any plants that are nearby. It is necessary to keep this water in good condition, and ensure that there is not a build up of mulm and other debris.
You will have to be careful with any new plants to ensure that there are no parasites on the roots, and also make sure that you do not use any poisonous plants.

Q. It is intended to start building in late Feb or March when the main ice and snow (if any) has gone - we tend to get mild winters in the Peterborough area. This will require the moving and storing of the fish in a filtered 750 gallon insulated tank, this in turn will mean I will be fibre glassing in say late April ie when the temperature will allow the fibreglass to set correctly.
There will be plenty of time to settle the fish into their new home, establish the filters etc and get some pleasure from the new pond before Autumn sets in. I realise that I may lose the odd goldfish but am I subjecting the koi to unnecessary risk by moving them in these cold conditions?
If so at what temperature would you recommend beginning this and moving them?

A. Ideally I would not move the fish once the temperature is below 46 degrees.
You do not say where the quarantine tank is to be situated, and so what temperature it will be maintained at. The temperature of the holding tank should not be more than a couple of degrees higher than the pond temperature. If the fish have been in temperatures below 50 degrees F then their immune systems will have switched off and when it comes back up through the fifty degrees then this is the dangerous time.
I would prefer to bring the fish into the holding tank before the winter and try to maintain the temperature at 55 degrees with only minimum feeding. It is important that the filter on the holding tank is mature and preferably use some of the media from the existing filter.
The goldfish are much hardier than the koi and it is the koi you need to worry about as they are at their weakest in the spring with the low temperatures starting to rise.

Q. I am going to be building a Koi pond next year (fingers crossed) and I would be grateful of a few answers to my questions.
1) Is there any specific rule to the depth of the concrete base to a ponds gallonage.eg. 3inch of concrete per 2,000galls?.
2) If I have no room to build a holding tank (heated) for the Koi in winter, what is the best way to heat and insulate your pond? Also can you set up the filter to run the pond in summer then the holding tank in winter?.
3) Can you use 9inch hollow concrete blocks filled with concrete instead of the 18x9x4 inch blocks?
4) Would you when waterproofing with G4 use clear or coloured G4 for the pond?

A. The following is the general answers to your questions: -
1). The depth of the concrete base really depends on the depth of the pond, and to some extent to the length and width. For any reasonable sized pond it should be at least six inches of reinforced concrete, and this is the minimum if you are fitting bottom drains.
2). I am not sure why you need a holding tank as your fish are better off in their main pond. In North Yorkshire the weather can get quite cold, and a heating system is worthwhile. However many people are unable to go to this extra expense and some sort of cover over the pond is necessary to keep away the cold winds. The majority of koi-keepers do not have a heating system.
3). Nine inch concrete hollow blocks can be used, and are just as good as 18 x 9 x 4 inch concrete blocks. The only disadvantage is the weight of them, and they are very difficult to align once laid on the wet cement.
4). You can use either, but most people seem to prefer the black as it shows up the fish better than light colours. In any case it will change colour as algae grows on the side of the pond.

Q. I have really been lucky with my pond project this weekend. I helped out someone last weekend in Derbyshire and found a supply of limestone, legitimate and for free! This is for the rockery and waterfall and will save me about £150. I brought 25 pieces back and will go again next week for the rest.

A. I am pleased to hear that you have obtained rocks for your pond surround and the waterfall, but I am a little concerned that you mention lime stone for the rocks. In this area we do use limestone (in fact there is very little else here) but it is very hard and does not leach out the lime into the water. It is very important that you check this out because if there is any possibility that the lime will leach out then it will be necessary to paint the rocks with clear G4.

Q. My koi on ocassions come to the very shallow water an the ponds edge. They are on top of the pebbles with the result that almost 50% - 60% of their body is out of the water. I thought that may be their bellies are itchy but to be honest I haven't got a clue. Do you know of any reason that they would do this.

A.The problem you describe with the pebble beach is quite common and something that koi always do. We strongly recommend to our members that they do not have pebbles in a pond because of this, and the possibility that they will damage themselves. The pebbles also tend to end up with a lot of blanket weed and other debris attached to them and are very difficult to clean.

Q. I'm just a beginner and was looking for information on different types of waterfalls.
We have just bought our house which has a small pond (750-800 gallons) and I am not having any luck on finding any information. I live in North Yorkshire, UK.

A. As you probably know it is possible to purchase ready made waterfalls at the garden centres, but I do not think they look very authentic.
The best way to build a waterfall is to put in a concrete base, arrange rocks so as to make three small pools each one higher than the other.
The rocks are then cemented in, and it is then important to treat the cement to seal in the lime. PoolGlaze can be used for this and obtainable from any Water Garden or Aquatic Centre.

Q. To save money I'm thinking of using stand pipes but how exactly do they operate ,what fittings do they use? How do they seal themselves?

A. Stand pipes were commonly used ten years ago, but due to the reduced prices of slide valves these valves are most commonly used now. Several companies used to supply the stand pipes ready made up, but these no longer seem to be available. Ball valves are the best solution, but are more expensive.
If you are using push fit waste pipe then you can put vaseline on one joint and then it is reasonable easy to pull out and reinsert the pipe. Always have a spare rubber O ring available. You have to be carefull that the pipe is always fully replaced, and if we have a very cold winter then ice can cause problems.

Q. I have pea-soup water (algae) that I'd like to eliminate and make the water clearer for aesthetic reasons. I'm looking at buying a swimming pool sand filter and pump. I don't see where you've talked about these. Is there a reason that people don't use pressurized sand filters (as used with swimming pools)? My pond is 12' x 6' x 4'6" with goldfish and plants.

A. Swimming pool sand filters were very popular in the UK some fifteen years ago, but now most members prefer to have large biological filters. Some do have the sand filters after the biological filters to further polish the water.
If you intend to use just a sand filter then I think you will have problems with the sand clogging up very quickly. I was in Capetown, South Africa, last year and I visited several koi ponds. Most of these were using only a swimming pool sand filter, but instead of using the sand they were using 5 or 6mm gravel or silicon chips.
In South Africa and the US they have many private swimming pools so it is easy to get parts etc for the sand filters. In the UK due mainly to the weather very few houses have swimming pools so it is difficult and expensive to get spares.

Q. On a similar point, and I dont want to run before I can walk,where would the central heater pipes enter the set up? In years to come this is going to be an item I'm sure will be on the cards.

A. The stainless steel heat exchanger will connect into the pipework between the main pump and the UV or venturi. You will need space for the boiler of course but the only other space required is for the heat exchanger, central heating pump, and the pressure chamber. It is a good idea to have as much space as possible in the pump chamber so that you can fit a different type of pump or UV etc at a later date without having to knock down walls. It might look very neat to have everything in a confined space, but when you come to change an item later it will usually be bigger and/or the inlets and outlets etc are in a completely different place. Remember also that the UV tube has to be removed sideways through the unit. The tubes should be changed once a year assuming you do not use it in the winter, and these are 3ft long.

Q. Does a winter covering have to be transparent?

A. Yes other wise the fish will lose their bright colours. This happens even in a dealers where there is little direct daylight. Ideally you should use horticultural clear plastic.

Q. What size of UV lamp should you use for a 6,000 gallon pond? What is the length of the tube, and how do you remove it from the unit when it needs to be changed?

A. As you need 10 watts per 1,000 gallons then two 30 watt tubes will be required. With ponds of 5,000 gallons or more it is quite common now to use a 55 watt unit.
The length of a 30 watt tube is 35 ins, and the 55 watt is about the same. If you have your pond two foot above ground then the pump chamber will also probably be two foot above ground. You can leave a hole in the side of the chamber to pull the tube through and then have something to cover the hole the rest of the time. The alternative is to have unions on the pipework attached to the UV unit. You then shut off the pump, close the valves, undo the unions and lift out the whole unit after pulling out the electrical connections to the tube. If you live in an area with hard scale then you will also require to remove and clean the quartz tube at least once a year. In Cardiff we do not have that problem as the water does not cause scale. You have to be careful with the quartz tube as they break easily and cost £35 each.

Q. Does a pond set up like those shown on the website make fish death less likely, or has anyone lost a good fish at some time?

A. Fish deaths are usually caused by bad water conditions, and even with a large well built pond you have to ensure that everything is running well. Some people will lose fish in any type of pond, but there is much better chance of the fish surviving in one of these ponds with a large good designed filter system. This type of deep pond is essential for large koi over 20 inches as they need plenty of room to develop the correct shape etc. You may not have large koi at present, but they will soon grow. The art of good koi keeping is the water quality.

Q. On this subject would it be feasible to top up or initially fill a big pond with rain water via a drain pipe?I remember reading somewhere that this water was dodgy due to it being untreated in that it hadn't passed through the water company filters.

A. Rain water is not recommended for filling or topping up a pond. In fact many serious koi keepers with show quality fish partly cover their ponds to keep out some of the rain. The rain water can contain chemicals, and anyway has a very low pH and is not ideal as it has not been treated as you say.

Q. I suppose like most people from the outset, I was pretty shocked, not only at the cost but the incredible amount of work involved, in what by koi carp pond standards was going to be a pretty small pond.

A. The amount of work actually involved is never appreciated by anyone until they have actually done it themselves. Even wives who are very enthusiastic at the beginning, and when it is completed all say "never again". Besides the 800 blocks, sand, chippings etc all over the place it is impossible to keep everything clean no matter how careful you are. Somehow sand and dust always seem to end up everywhere including the bedroom.

Q. From a construction point of view the biggest problem I encountered was from the comparitively low water table in my garden. Every single day I would spend what seemed like ages bailing out gallon after gallon of water.I thought, once I had laid the first course of blocks this would cease to be a problem, but of course unrendered concrete blocks as you know soak up water like blotting paper, anyhow I got there in the end.

A. The low water table, and or heavy rain is often a problem. We usually recommend a sump being dug so that a submersible pump, preferably with a float switch, can be used to keep it relatively dry.

Q. Just after I'd finished making the excavation walls vertical, a chunk of the wall collapsed in! I would imagine that in a really deep pond, extreme care must be taken to avoid serious injury.

A. This is always a problem, and I do not know of anyone who has not had some type of landslide, especially if you take several weeks to complete it and there is a lot of rain or even very dry weather. Great care must always be taken, and you should always have someone outside of the hole at all times that someone is in the excavation.

Q. My present pond has a couple of thousand gallons in it. Would there be an advantage to transferring this water to the new pond or should I fill it with fresh water?

A. I would fill the new pond with fresh water, and use any filter media from the old pond to help seed the new filter.

Q. When someone has built their new pond, where do they purchase there new koi from and what quality:-

1. Do they buy large good quality koi
2. Small quality koi
3. Cheap small/large koi
4. Do they export quality koi.

A. All of these four are correct and it depends which way you want to go with the hobby.
Some people are happy to have just pond fish which then become family pets, and at the other end some travel to Japan and purchase large high class fish possibly with a view to showing.
There are quite a few people that prefer to buy smaller fish and grow them on themselves as they find this more rewarding.

With a new pond, especially if you do not include some media from an old filter then you are likely to get "New Pond Syndrome" This is ammonia and nitrite spikes which can effect the fish.
With a new pond I usually recommend that people buy some larger fish that other koi keepers are willing to sell because their ponds are over stocked, or they are buying better fish. These are cheap and usually more hardy than fish which have just come in from Japan.