I mentioned earlier on that I would like to build a QT pond behind my existing filter system, as well as a new pond next to the BBQ area. Since I will only have 2weeks to do this, I have changed my mind again. The idea is to build only one pond next to the BBQ as this should fit in nicely with the current setup. I want to ‘steal’ some water from the current filter / motor setup to feed the new pond. This pond will be mostly above ground level and about a meter deep. I want to use a waterfall return to the main pond. The idea is to use a filter system (gravity fed) at the point where the water returns to the main pond via the waterfall. This will also be the point where I fit the skimmer and bottom drain.

Hopefully this will work.

My idea is to fit my 2 small spare pumps to the new pond as well. If I want to use this pond as a QT tank I can shut the water flow off coming from the main pond and switch the 2 pumps on. Now I will have no water flowing into the main pond anymore and this pond will operate independently.

I will start on this project in about 2weeks from now and would like any input from your guys before I make a mistake again.

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2 Weeks? Good luck mate

It’s going to be a nightmare. The main pond was constructed from scratch in 14 days ( 12days – first and last day I traveled) Can’t fit a back actor in to dig the pond, so most of the pond will be above ground and still have to check the available space out, but I think the pond will be in the region of 5000 – 7000L.

I still have a small EzBio pre-filter that can handle 9000L/h water flow. Might mount the 2 submersible pumps inside a square plastic box with the pre-filter as input to the box to keep pumps clean. A few Matala sheets as filter media. Pumps only to be used when I switch the main water supply off to use pond as independent QT facility

So the QT will have seperate filtration from the main?

Yes, so that the pond can operate independently from main pond if I need to. Under normal operation it will use the big ponds filtration as well as its own, to minimize the load one filter only

Ah ok. I'm sure it will work fine then

I would do the two ponds independantly from each other, especially in view of the fact that you have the equipment already.

Don't put all your eggs in one basket.

If you encounter a problem in the main pond, you will probably also have problems in the QT pond, and visa versa, and then it is too late to separate the two systems.

An extra pond should act as hospital pond or QT pond or emergency pond(for maintenance etc) and for possible spawning, separate from your main pond.

Do you plan to have a lot of fish in the QT pond? and if so, take them out everytime you get new fish? or only keep new arrivals?

I believe a QT pond should be separate, only have a few "feeder fish" to keep the system/biofiltration going and to provide company for new fish and to settle them down and it should be available in case of emergency or for new purchases and should always have a low bacterial count low organic matter, no plants, and have a high salt concentration.

Thanks Paul

It makes sense to run it separate for health purposes.

At first I think I must spend a day to stress up all the Koi in the main pond by catching all the unwanted fish that I want to get rid of. I have 51 fish in the main pond and many came from my small pond. I might run into trouble with overstocking soon, so it is better to give them away before they become too big. I might have a problem to find new owners in Bloem since we don’t have many Koi keepers.

Second question: Where can I find a suitable pond heater? I assume they come with an adjustable thermostat for precise temperature control. I have not seen one before, but I am sure they must operate in a similar way as the aquarium heaters, just much larger.

I guess it will be a swimming pool heater. Smallest I could get a quote on was 2kva if I remember and it was like 10k..

Thanks Cameron

I did a search since my previous login and see Ultrazap and Superpumps sell these items. 2kW for R1130 and the 3kW for about R100 more. Looks like the Ultrazap UV units. The elect. bill will be huge and I will need to upgrade the wiring to the pond from 2.5mm to 4mm to run all my toys.

For a matter of interest:

2.5mm wire = 15A = 3.3kW load
4mm wire = 32A = 7kW maximum load

It is going to cost you big time on electricity charges and the winter is on it's way out.

The heaters used for aquariums is not an option. The heat pumps are much more economical, but still very expensive to run.

Why don't you consider to enclose your QT pond with glass in stead and run some of the water through black irrigation pipe via your roof?

Instead of running my heaters, I have just created a hospital/QT facility in a hothouse which I have build with normal greenhouse plastic, and I am amazed by the temperature difference. Have not filled it with water yet, but the air temperature inside goes up to 38 degrees while it is 15 outside.

Yeah the ultrazap heaters and swimming pool ones are a bit different

My brother spent 18k on a heatpump for his 45,000l pond and it could not lift the temp more than 2 degrees. That is a hell of a lot of money and electricity for very little gain. He switched it off after two weeks.

Hi Maruis,
I would run a new pond on a total separate systems, many more options and can also be a secure QT pond when required.
I am currently running a ultrazap 2kw heater on a 2000 Qt (Vat) to treat a very expensive Koi and give her a fighting change over the winter period. Believe me extremely expensive to run a heater. Paul have given you a good option.

Thanks for the advice guys. 3kW is what I will need and I agree it is far too expensive to run. Same as 4 x 750Watt motors. I have 2 in use on big pond plus 3 x 55W UV's. Hopefully the Free State sun will help me since both ponds will be in full sun

why not setup a solar panel which you can redirect the water flow back to your pond thru???, then if you find your water temp is abit high you can always bypass the panels via the redirector piece like in a pool setup. Just do a mini DIY solar setup with 15 or 20mm HDPE piping also with a redirect valve. The piping is about R1.80 a meter and wont cost you anything on electricity and you can build a solar panel on ground level so you would still be able to use a submersible pump on it.

I'm attempting DIY solar heating on my spa pool this summer, thats my next project now after my pond

Hi Cliff

Thanks for the advice and I know solar heating is a winner. When I stayed in Pta I had it on the swimming pool and it raised the temperature a lot and water was hot even late in the evening.

The only problem I foresee in a Koi pond (winter) is that you will have a high temperature during the day, but the temperature drop during the night might be huge. Hopefully by the time I need to QT fish in the new pond we will be in summer and the temp will remain in the range as required for the quarantine.

Quote :

The only problem I foresee in a Koi pond (winter) is that you will have a high temperature during the day, but the temperature drop during the night might be huge

Therefore having the redirect valve, would be a hassle tho having to switch on and off every day

Cliff, do you just use that piping in a weave and it will work?

Not so much in a weave, easiest method is to coil it, I'll try and do a "Marius MS Paint" image

my drawing looks absolutely crap, so let me rather explain.

I would take the 20mm HDPE piping and coil it into a circle, with the outer circle containing the outlet from the pond, this would then coil around till you reach the inner bit of the coil which would then feed back to the bypass valve and then back to the pond. Obviously you cannot have any kinks as you will then have leaks. But I was thinking for a pond to mount this onto a floor standing board which is sun facing.

On your inlet and outlet you would have your joins which feed from and to the pond where you could then bypass at your discretion.

Found a pic which I saw a while ago which is an excellent example

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I wonder how well this works.

Usually the pool guys say 50% of of your surface area needs to be in piping for the solar heating to be effective..

Well, you dont really want the same level of heating a pool can get, so i'm pretty sure 15 - 25% of the surface area would give your pond a decent temperature

Cliff wrote:

if you find your water temp is abit high you can always bypass the panels via the redirector piece like in a pool setup.

The idea is good, but, then you will have to run it 24/7 and not put it off from time to time.

If you close this system when it is warm and run it again hours later or maybe the next day or next week, the water inside the pipes might overheat, causing the pipes to brake. When you put the system on again, you also might not realise a leak caused by the exposure and heat, until you find your pond empty.

More important, think about how the anaerobic nasty bacteria will grow in that heated standing water with no oxygen within a couple of hours. When you open the system again, all that bad bacteria will flow into your pond, and might cause serious health problems.

Photos are looking good and it is a simple and cheap modification to do on any setup. As you say, you can bypass the solar heater when you don’t need it. The temperature will rise a bit during sun shine weather, but in the Free State we have cold nights during winter, so I wonder what the experts will stay about this massive temperature swing?

Will this not have a negative effect on the Koi? I don’t mind the cold temperature in the winter since I believe they need a ‘rest’ period as well. My concern is more towards QT in colder weather and how stable must the temperature be for QT to be effective?