Backyard Aquaponics
A place to discuss aquaponics

Hi

I have a large pond (7000 l) as part of my system


I have to run an uv filter about one week every month in summer time or the pond turns to pea soup. Plant growth stops if I don't run the uv filter.

I read somewhere that the uv filter causes iron to be precipitated. You may want to add some iron if you run a uv filter.

Gabe

I recently had to clear the water in a pond like yours. I just used mechanical filtration by means of a 6500l/h pump going into a polyester stuffing pillow. Ran it for 2 weeks and pond is crystal clear.

When I cleaned out the pillow I had litres of thick green sludge coming out. Probably the same stuff as your growbeds and what is causing oxygenation problems for your growbed.

Everyone told me mechanical filtration wouldn't work... But in my case it did.

Im having similar issues with green water and with all my limited research as a new AP I have done everything I can think of including
1 testing water,
2 doing a 20% flush and replace,
3 adding chemicals as advised by my local aquarium expert (over $70 worth!)
4 putting in floating grow beds to reduce surface area for light ingress
5 enclosing my IBC sump with black non reflective covers to exclude light.

My next strategy is to do as you suggest and install a mechanical filter. Can anyone point me to a site showing designs for mechanical filters that work? I have about 2400 lit and now only 8 trout - I lost 5 in recent weeks.
Any help most appreciated,
Marticulus, Bunbury, WA

If you're going to buy an external filter... buy a canister filter... with UV...

The UV will clear your algae quite quickly...

RupertofOZ, I am unsure where to get one of these in WA. What do they look like? Any web places with pics?
Marticulus

found a pet shop that sold me a pressurised UV filter and as soon as this shitty weather improves I will install and hope for a good result.
Water is very green and so any improvetn will be welcome.

The UV is a good thing for dealing with algae, however, a pressurized filter might be problematic if you don't have a pump that can provide enough pressure to the filter.

will let you know after the weekend (weather permitting)
Marticulus

Would be nice to get some UV myself. Had enough of wind and rain.

I think it will be sunny and calm between 12 and 3 pm this Saturday, just when the Dockers are playing that team from Melb, then it will return to the same old we have had for the last month.

Goodluck Marticulus

Last weekend's game was spectacular! Tried to get tickets but no luck. Got to go to a wedding straight after this Saturdays game so cant play up...
Looks like Sunday is Aquaponics filter install day and another contribution to Bunnings super fund...grrrr
Marticulus

So that's what, a 19 000 litre pond with 600 odd litres of growbed, with 15 fish.

Surely with this amount of water the nutrients coming from 15 fish will be severely diluted, not to mention the competition for nutrients with the water plants and algae. Does anyone else see this as an issue?


How much and how often are you feeding your fish?

The biggest problems I've seen/heard of with really big volumes of water and tiny amounts of grow bed is that you don't have much filtration from just the grow bed so if your pond/swimming pool doesn't have additional filtration and circulation than is possibly through a tiny grow bed, issues with water turgidity and algae can be a huge problem.

As to nutrient levels, well if it is already a balanced pond with water plants already using up all the nutrients, there may not be much left over for the veggie bed (especially considering that pond plants and aquatic plants often use ammonia directly before it has much chance to be converted to nitrate.)

If it is not already a balanced pond and it requires water changes weekly to keep the nitrate/phosphorus levels down, then the addition of a veggie bed can reduce/eliminate that need if the bed is sized correctly.

A large expanse of water with ample nutrients and not easily covered or heavily shaded often has issues with algae though.

As to the idea of dilution. Perhaps instead of thinking of it as dilution you can think of it more like you need to build up your bank of nutrients. Trying to cycle up a HUGE pond with only a small grow bed has the issue that it takes a long time to really get the cycling started with fish. If the pond has been around a long time though, I already has bio-filtration going on. If the bio-filtration can keep up with the fish load then the only real question is are there enough nutrients left over to grow any veggies. That is easy to figure out, do a nitrate test. If the nitrate shows 0 then it might be hard to feed the small quantity of fish enough to provide enough more nutrients to a veggie bed. If the nitrate test is orange or red, give the veggie bed a try. It isn't the volume of water the nutrients are in so much as the balance of what is getting used compared to what is being produced.

Well said TCLynx.

I have noticed a trend with large ponds and very long cycling times.

Providing you have sufficient mechanical filtration to address the algae issue you mention, in a larger pond you also have more surface area for the Nitrifying bacteria to colonise on the pond walls itself so this surely must increase the stocking densities somewhat

To give you an example, I know someone who has kept about 5 goldfish in a small pond in the shade with no pumps or filters, no water turn over whatsoever.. and they've been living happily for over 5 years like that. The fish are lightly fed. Not recommending this of course, but there must be enough surface area in the pond itself for sufficient biofiltration to occur

I expect the biggest danger in systems without any sort of pumping/aeration or circulation is that if it gets really hot, the pond could become dangerously low on dissolved oxygen. If there are any pond plants in that lightly fed natural pond, they may be using up some of the ammonia before it even needs to be converted by the nitrification bacteria. Pond plants are incredibly good and using up nutrients as long as there is enough aeration or minimal enough stocking to keep the fish from suffocating overnight.

I finally installed the UV filter I bought from local pet shop. It is a PONDONE Claritec 3000UV. The result is spectacular!!! All algae gone in 9 days. Worth every penny. (About $230 AUD). I have since permanently run wiring to an external power GPO near to the system which was last weekends job in between watching the footy grand finals and participating in a wedding. Now all I need is some good weather to prompt the plants into growing. Next project is to buy some silver perch and marron into the system to join the trout.
Wow what a hobby...
Marticulus