5 replies to this topic

[Skuts]

Hi all,

Looking at putting a pond in but was wondering what you do about nitrates, in my aquarium I do weekly water changes but a pond is so much bigger so what do people do? Are water changes needed or do you put plants in the pond and they keep the nitrates at bay?.

Cheers

[bigjohnnofish]

plants will help..... but i have found over the years its not easy to accumulate high nitrates in outdoor ponds in full sun... unless mega heavily stocked.....

perhaps if you get high nitrates you can circulate the water through a grow bed and grow some of your own veges as well.....

and you can still do water changes in a pond....

attach a denitrator to your pond is something else you could do... although a bit extreme.....

[theonetruepath]

I have a filter in my pond I got from Aquotix. it has a 'back flush' feature. I just flip over a couple of valves and it pumps water into the garden through a nice long hose. There are also a pair of handles you crank up and down that run brushes over the sponges. After a few minutes of back flushing I switch the valves back and there is room in the pond for a 200l barrel of water which is conveniently hiding behind a tree stump where it has been aging for the last week.

I have a blue drinking water host attached to the same tree stump with an old hammer cable-tied to the end to hold it exactly at the bottom of the barrel. The other end I unroll to the pond and start the siphon going.

An hour later I come back and roll up the hose and refill the barrel.

It all takes over an hour, but the time I am involved is about 3 minutes.

I have a second barrel there too so I can do a double change/have extra emergency water available etc. A bit of shade cloth stops leaves/frogs etc getting into the barrels.

I used to carry water around in buckets but life's too short!

[Ivan Sng]

Well that's where Aquaponics comes in real handy... the vege/plant use up the nitrates, you get food and all you need to do is top-up the water due to evaporation and transpiration. No water changes required.

And if you design it correctly upfront, you don't even need expensive filtration, just a growbed that acts as both the mechanical and bio filtration.

Edited by Ivan Sng, 24 May 2011 - 01:54 PM.

[Skuts]

That sound like the way to go Ivan I was playing with this idea, how would it need to be designed so that the grow bed would act as both mechanical and biological filter??

[Ivan Sng]

Well for starters, in order for a growbed to effectively filter and break down the solids, it needs to be at least 30cm deep, filled with gravel that does not alter pH too much. So gravel like pea gravel and blue metal should be fine, but of coz expanded clay (hydroton) is the best but also the most expensive. Composting worms are placed into the growbed to assist with the breakdown of the solids... And as long as the water is highly oxygenated, the worms will survive fine in the growbeds.

Then for every 25 fishes (assuming they are of a breed that can reach 500grms each) you plan to have in your pond, you need about 500L (volume) of growbed. If the fishes are of a breed that would not reach 500grms, then you might be able to increase stocking numbers once the system is cycled.

There are a few ways of running growbeds, such as constantly flooded, flood and drain via timer, or auto-siphons. Each of the methods has its pros and cons, but with flood and drain via timer, you do not need to run your pump as much but you need to size your pump big enough to turn over one entire water volume of your pond in the time that the timer is running...

Select a pump that is good at removing solids and locate it at the lowest point in your pond. I found the Laguna Maxflo range to be pretty good, more expensive but great solids removal and low wattage.

If you need further information, feel free to PM me for more information.