Aquaponics and Waterlilies

[cando]

I Live in Capalaba, Queensland and I grow waterlilies and lotus in a pond 6m x 2.4m x 500mm deep. The plants are in 175mm plastic pots. I have Goldfish and Black Mollies in the pond to keep down the mosquito larvae and algae. I do not feed these fish at all. The pH in my pond is too high as is often the case with ponds in full sun. This causes deformities in my lilies.

I installed 3 bathtubs filled with pebbles set up higher than the pond. I circulate the pond water throught the beds with a flood and drain system on a timer - 30min on, 30min off. My main aim was to get the pH in my pond down from around 8 to around 6.5 - ideal for water lilies and lotus.

I have been running the system now for nearly a year and thought it had brought the pH down but that was only due to taking a reading in the morning. The readings in the afternoons are about 1 point higher which is normal for ponds in the full sun. I am trying to see if an onion bag full of barley straw will bring the pH down. So far the water lilies in this pond seem a lot healthier than those in my other ponds.

A couple of months ago I placed 25 Jade Perch in a black 220 litre plastic crate inside the pond. I drilled the crate full of 3/16" holes and the water from my grow beds flows directly into the crate. I also installed airation into the crate. I feed the fish on small sinking pellets I got from SE Queensland Fish where I bought my Jadies. They also get a fresh lettuce leaf every day which they feast on. The amonia and nitrite levels are very low in the pond.

Problem is a cannot see my fish in the black crate to see how much they eat. I placed a white plastic sheet in the bottom but that soils very quickly to a brownish colour. The fish are happy and growing. I only lost 2 to ich.

I am thinking of replacing the crate with a 300 litre, 500mm deep white bathtub full of holes. Only this time I think I will make the holes bigger to let the floating bits of muck flow through into the pond. Only problem is that it will let the small Black Mollies through the other way to become food for the Jadies.

Someone recommended more fish in the loop to bring the pH down trough greater microbial activity. That will have to be in a 1000 litre tank outside the pond since I cannot afford to lose any more pond surface space to fish crates. Also going into winter here may present a few problems with keeping them warm enough.

All the very best

Francois

[Murray]

Welcome Francois,
Good to see you here. We have spoken before and it is most interesting to hear about your project again.
GaryD wintered his Jades last year without heat and they did ok. I am going to do the same for some Jades (130) in one tank just to see how it works out. The Jades in question are around 150 to 175mm long
I have 20 Jades in another tank that are from the same batch and I will heat that tank just to observe the difference in growth.
Heating costs in winter are very high and only going to get worse as our Gov keeps jacking electricity prices up and up.

[cando]

Thanks Murray

My thinking is that with the very large body of water in my pond that it will keep the water warmer in winter. My pond has a brick and concrete wall of around 150mm thick which absorbs the heat from the sun during the day. The pond is also in a sun trap with trees on the South. I am thinking of covering the pond and the grow beds with plastic to act as a hot house for the winter period.

My fish are now around 150mm in length and I am planning to put them in the bathtub full of holes inside the pond today.

Francois

[KenR60]

Hello Francois,
My Pond is a year old now with around 80 Goldfish ( 200-250mm ) and about another 1000 natives. Its always been in full sun until about 4 weeks ago when I put up a Shade Sail ( 6mtr x 4mtr ) so now I have only about 4 metres of Direct Sunlight where the Shade Sail doesn't cover. Every Plant I add to the water or even my Aquaponics System just goes Balistic!!! Water is almost always clear enough to see right to the bottom also. My Filtration is home made. Your welcome to come over to have a look anytime as I'm not that far away from you.

[cando]

When I transferred my fish today from the black plastic crate to the bathtub I found hundreds of ramshorn snails feasting on the leftovers on the crate walls and sides. I use them in my ponds to help with the algae. They only ever eat decaying plant material. Don't know if they help to keep my fish healthy.

Francois

[cando]

Now that I can see my fish against the white background they are very scared of me. Whenever I come near they scurry away and huddle and mill together. I want them to be nice and tame like Murray and GaryD's.

I must say I enjoy watching them swim about when I stay out of sight.

Francois

[KenR60]

They should get used to you, just make a habit to feed them when you walk out there... Mine can hear the sliding door open and they can be 10 metres down the other end and by the time I'm closing the door they are nearly leaping out of the water waiting for me to feed them. I always feed them in the one place too.

[cando]

Pictures.

Francois

[aussieap]

Hi cando. I am jealous of all that water! You could run some serious food production there.
Your concrete tanks are the reason for your high pH, you prolly know that. Not such a bad things as typically we have to buffer to get our pH up over time.

[cando]

Picture of Jadies in their bathtub full of holes in the pond. They are hiding under the water inlet and airstone. I had difficulty attaching this picture before but figured it out.

Francois

[cando]

Hi Darren

These ponds are over 10 years old and painted with a penetrating 2 part epoxy paint inside. I doubt there could still be any lime leaching. I have the same high pH problem in a pond that has a rubber liner in it. I think full sun, not enough fish and the water lilies and lotus I grow in pots in the ponds during the season has something to do with the high pH. Except for the Jadies I don't feed my fish either so not enough ammonia.

I have been thinking about going commercial with aquaponics for some time. I have 5 ponds that size and about 7 or 8 round 2.4m diameter ponds and 30-40 bathtubs full of water lilies and lotus. Oh yes, and another pond out front of 7 X 4m kidney shape. All 500mm deep.

Francois

[GaryD]

Hi,



These ponds are over 10 years old and painted with a penetrating 2 part epoxy paint inside. I doubt there could still be any lime leaching.

I agree.....and here's my view on your pH problem.

I recall from our discussions that you fertilise your lily and lotus pots.

Elevated nutrient levels in the presence of low oxgyen results in denitrification. Denitrification causes the pH of the system to rise.

As an experiment, I propose that you aerate just one of your lily ponds so that you can rule out low oxygen levels as a factor.

If my belief is correct, your pH should gradually start to fall.....and the higher oxygen levels should be better for your fish and your plants.....and the lower pH will certainly make it safer for your fish in the event that your ammonia levels increase for any reason.

Gary

[cando]

Hi Gary

The water from the pond where I now have my Jadies has been circulating through the 3 bath garvel beds for nearly a year which increased the oxygen levels. I have also had an airstone in the pond for around 3 months. There still is very little difference in the pH between the ponds. This one sometimes is slightly lower than the others but with the morning and afternoon pH being so different it makes things confusing.

All in all the pH in all my ponds is high. When I clean a pond and fill it with rainwater from one of my fully enclosed tanks with a pH of 6-7 the pH is up to around 8 within a day or two without any plants in it. I still blame the sun:)

Francois

[GaryD]

OK....back to the drawing board.

[cando]

I have just checked the pH in a number of my ponds. All the big ponds are just off the scale blue that my colour swatches show which ends at 7.4. I only have a Junior pH testing kit but it uses the same Bromothymol Blue that the bigger ones use. The only exception was the pond that has a pond liner in it. It was 7. Last time I checked it it was closer to 8. Some of my ferrous cement ponds were also high in the sevens and one was 7. The surprising pond was a square, 2m X 2m fibreglass pond where I had mature lotus plants in 9 litre plastic basins until a couple of weeks ago. Now there are only floating plastic bread crates to keep the ducks out. The colour was a deep indigo. The lotus were moved in there long after they were planted and fertilized. I only fertilize when I plant and it is Organic Life or Organic Extra pellets wrapped in newspaper buried deep in the soil that I plant the lotus in. I test the pH of the soil I use and it is usually slightly acid. I top the pots with 2cm of medium river sand with a pH also around 6.5 - 6.8.

My mate at Suncoast Watergardens has the same problem. His internet contacts aslo have a problem with high pH in their fully sunned lily ponds - lilies have to grow in full sun.

Francois

[cando]

I want to keep my fish warm for the winter. I was thinking of putting plastic over the PVC pipe tunnel I use for the netting to keep the ducks out of my pond. But I realise it is too flimsy, especially with the wind we get around here sometimes closer to the Bay.

I think I am going to make a timer frame that sits on the wall of my pond, about 300mm high accross the middle and about 100mm on the two long sides. I am going to make a truss for each end and also where I have the PVC pipes. Connecting the trusses up with timber to make a rigid frame. Something like GaryD has over his duckweed pond.

Still undecided as to how to do the plastic. Maybe rolled up and down from the sides to the centre on a sand filled 40mm PVC pipe each side to hold it down, and fixed to the timber frame in the middle. The other possibility is 4 smaller plastic covered timber frames each side that just rest on the frame, maybe clamped down to keep them from blowing off.

I will probably have to open the plastic up every morning and close down again in the afternoon during winter which makes the pipe option more attractive and less work than removing and replacing 8 frames each day.

I will of course also cover my 3 bathtub grow bed in a mini greenhouse with opening sides like GaryD did but that is straight forward by comparrison.

Any ideas will be welcome at this thinking stage.

Francois

[KenR60]

Seems like a bit of expence, if thats not a big problem maybe do a 70x35 Frame and either do the Thicker Plastic of even Glass?

[cando]

I cleaned out the pond today where I had the 20 Jade Perch who had to fend for themselves eating Elodia and small tropical fish that abounded in the pond - Platties and Black Mollies.

I caught 21 of the 20 I bought (Matt at SEQ Fish is generous) but they were only quarter to half the size of the 24 Jadies I have in the bathtub where they get fed - both sets of fish were bought at the same time.

They were too small to put in the bathtub and I had to put them in a black plastic cage I used before. There was also a great difference in size between the largest and smallest fish I caught. The biggest one was more than twice the size of the smallest one who was not much bigger than when I bought them. It would be interesting to see how fast they will grow now.

Francois