The Baby Q

[GaryD]

Hi,

The seedlings in the Baby Q grow bed are now three weeks old. The lettuce will be ready for picking in the coming days.

Gary

[GaryD]

Hi,

I cleaned out the settling tank/clarifier on the Baby Q yesterday. It had accumulated a heap of solids in the fortnight since I last cleaned it out. I syphoned the watery solids into my aerobic digester and they're currently brewing away.

I'd like to come up with an easier way to maintain the settling tank/clarifier.......probably by replacing the nylon bird netting with Kaldnes K1 (so I can clean it by bubbling air through it)......but, in the meantime, this is OK.

Gary

[DaveOponic]

Gary,

Sounds like the new system is performing well. I have found the easiest to clean are the "toilet brushes" in the top of my 200 litre drum swirl/biofilter.
I was given a truckload of aquarium gear by a friend who was liquidating his Koi collection after suffering a huge loss of fish. He gave me quite a range and quantity of filter boxes, foam and other equipment, half of which I haven't used yet.

By far the best are these "brushes" that provide a huge surface area for biofilm and are so easy to clean. The Japanese filter foam (sorry, I forget the name) is also easy to wash with the hose. The Kaldnes too are OK but seem to not want to give up the muck as easy as other media.

This guy also had what I thought was a great idea and that is he used clay balls (Hydroton) in what I call onion bags. These are really convenient to stack in the filter box and very easy to wash clean with the hose.

I am thinking of setting up a solids digester like you have described, At the moment, I drain my solid waste from the big filter out onto the lawn. It is the greenest and healthiest patch of lawn in the yard but I have to mow it twice as often!!!

My Koi tank has been running crystal clear lately for nearly a month despite having about 20 Koi over 1kg, some 2 or 3kg and equal numbers of Tilapia, all up over 50 fish in 1000 litre tank.

[GaryD]

Hi Dave,

Sounds like the new system is performing well.

It's going OK......but there's still plenty of room for improvement.

I'd like to see more water going through it......to the point where I can use the inflow from the sump tank/Moving Bed bio-filter to 'sweep' the tank bottom.

I originally designed this system with jade perch in mind but it's currently got 15 largish barramundi in it. As you're aware, they have different faecal habits and, at the moment, I still have to remove some of the solids manually.

I might also swap some Kaldnes K1 for the nylon bird netting in the settling tank/clarifer. While it doesn't take a long time to clean, I think that the K1 will probably do a better job for what I want.

I have found the easiest to clean are the "toilet brushes" in the top of my 200 litre drum swirl/biofilter.

Have you posted a photo of the 'toilet brushes' yet?

I also like Matala mat as a clarification media. It's easy to clean, its robust (unlike some of the filter foam products that I've used) and it comes in various densities.

I was given a truckload of aquarium gear by a friend who was liquidating his Koi collection after suffering a huge loss of fish. He gave me quite a range and quantity of filter boxes, foam and other equipment, half of which I haven't used yet.

By far the best are these "brushes" that provide a huge surface area for biofilm and are so easy to clean. The Japanese filter foam (sorry, I forget the name) is also easy to wash with the hose. The Kaldnes too are OK but seem to not want to give up the muck as easy as other media.

While I think that the Kaldnes media is designed specifically for use in Moving Bed bio-filters, I suspect that it is also useful (in a static situation) for water clarification. I don't think it matters if not all of the muck comes off. The particulate matter will stick to the remaining bio-film.

The easiest way to clean it is to use air to make it churn. The action of the media rubbing against each other causes the muck to slough off. Once you've done that, you switch the air off and allow the particulate matter to settle out prior to draining it off.

This guy also had what I thought was a great idea and that is he used clay balls (Hydroton) in what I call onion bags. These are really convenient to stack in the filter box and very easy to wash clean with the hose.

I've seen this used, on a small scale, in some filters.

I am thinking of setting up a solids digester like you have described, At the moment, I drain my solid waste from the big filter out onto the lawn. It is the greenest and healthiest patch of lawn in the yard but I have to mow it twice as often!!!

The aerobic digester is really cheap to make and easy to operate and, every time I see how much sludge is syphoned off, I get a really satisfying feeling knowing that all of that muck is going into my worm beds rather than remaining in the system.

It's been a struggle but I'm happy that I'm finally getting people to understand that keeping solids in a system is arguably the most over-rated idea in aquaponics.

My Koi tank has been running crystal clear lately for nearly a month despite having about 20 Koi over 1kg, some 2 or 3kg and equal numbers of Tilapia, all up over 50 fish in 1000 litre tank.

They're both dirty fish so your filtration system must be working well for you.


Gary

[Crusty]

Hi,

I cleaned out the settling tank/clarifier on the Baby Q yesterday. It had accumulated a heap of solids in the fortnight since I last cleaned it out. I syphoned the watery solids into my aerobic digester and they're currently brewing away.

I'd like to come up with an easier way to maintain the settling tank/clarifier.......probably by replacing the nylon bird netting with Kaldnes K1 (so I can clean it by bubbling air through it)......but, in the meantime, this is OK.

Gary

Hi Gary

Is the attached a photo of your clarifier? If so, can you explain what is going on there? I am confused. You have netting in the clarifier and want to replace it with kaldnes? If you are using it as a packed media filter, I may be able to help if that is the case...

[GaryD]

Hi Paul,

You can see a photo of my filtration system for the Baby Q here.

The water flows by displacement from the fish tank (by way of a standpipe which draws from the bottom) into the top black tub. This is a settling tank and clarifier (filled with nylon bird netting).

As it enters the settling tank, the water is forced to the bottom of the tub and makes its way through the bird netting (with a view to trapping the suspended solids) before leaving the tank through an overflow weir.

The water then drains to a continuous flow (subsurface) grow bed located on the other side of the shed wall. It travels the length of the grow bed and drains back (through the shed wall) into the bottom tub which is set up as a sump tank and moving bed bio-filter (filled with Kaldnes K1).

I have set things up so that I can bypass the grow bed (in the event that I want to treat a disease or infestation in either plants or fish......or to minimise overnight heat loss) and the water will just drain from the top tub to the bottom one.

A pump located in the sump tank/bio-filter lifts the water back up into the fish tank.

You have netting in the clarifier and want to replace it with kaldnes?

Yes. I've been thinking of replacing the nylon with K1 (static) because I think if might trap suspended particulates more effectively (much greater surface area) and I can set things up so that it is easier to clean.

Gary

[Crusty]

You can see a photo of my filtration system for the Baby Q here.

The water flows by displacement from the fish tank (by way of a standpipe which draws from the bottom) into the top black tub. This is a settling tank and clarifier (filled with nylon bird netting).

Yay for positive displacement in the fish tank!! Good thinking Max.

As it enters the settling tank, the water is forced to the bottom of the tub and makes its way through the bird netting (with a view to trapping the suspended solids) before leaving the tank through an overflow weir.

It will indeed trap the solids if it is packed tight enough. Is the "overflow weir" set up to skim from the surface?

The water then drains to a continuous flow (subsurface) grow bed located on the other side of the shed wall. It travels the length of the grow bed and drains back (through the shed wall) into the bottom tub which is set up as a sump tank and moving bed bio-filter (filled with Kaldnes K1).

Cool. Not in the order I would do it but it will work just fine. I would have the grow bed after the bio so the nutrient is "inoculated" by the bacteria into a more usable nitrogen form (nitrate) before it gets to the grow bed. But either way will work.

Sidebar: You asked earlier the ratio of K1 to water volume is generally 2/3 media. Example: if you have 90liter bio, fill it with 60liters of K1. Best to have a tap for the air supply so it can be adjusted to get the media "rolling" not "boiling". Meaning just turning over and lightly bumping into each other, this keeps the media in a "fresh state" which is most efficient. Sort of like a simmer on the stove.

I have set things up so that I can bypass the grow bed (in the event that I want to treat a disease or infestation in either plants or fish......or to minimize overnight heat loss) and the water will just drain from the top tub to the bottom one.

Perfect. Now it is only from my way of thinking, it can be done any way you like. My preference, is the same Gary, the two separate systems should have the capability to be isolated from each other. Very hard to do without a bio filter...

Yes. I've been thinking of replacing the nylon with K1 (static) because I think if might trap suspended particulates more effectively (much greater surface area) and I can set things up so that it is easier to clean.

You will find the K1 will work very effectively as a packed media. If you already have a way to set it up to clean, great!

-

In general all the aspects are there for a great little set up. For the small foot print a bio filter takes and for the safety it provides, it is my opinion all aquaponics should have included as part of their system design. Personally, Gary I would arrange things a little differently but I think what you are doing is just great.

[GaryD]

Hi Paul,

Yay for positive displacement in the fish tank!

This is what we refer to as the CHOP system (constant height/one pump) and is an adaptation of the water trail used in the UVI aquaponics system......but for use with grow beds rather than raft tanks.

It differs from other AP system layouts in that the pump is mounted in the sump rather than the fish tank.

It will indeed trap the solids if it is packed tight enough. Is the "overflow weir" set up to skim from the surface?

Yes.

Cool. Not in the order I would do it but it will work just fine. I would have the grow bed after the bio so the nutrient is "inoculated" by the bacteria into a more usable nitrogen form (nitrate) before it gets to the grow bed. But either way will work.

The reason that I opted for putting the bio-filter at the end of the water trail rather than straight after the settling tank/clarifier was that any suspended solids that made it through the settling tank/clarifier would be trapped in the grow bed. This would mean that the bio-filter would only need to deal with dissolved solids.

My rationale was that I wanted the water that went from the sump to the fish tank to be in the best possible shape in terms of nitrification and aeration.

Thanks for the K1:water ratio. That's very close to figures that I'd got from another source.

I still have some work to do to get the correct 'rolling' action happening.

Perfect. Now it is only from my way of thinking, it can be done any way you like. My preference, is the same Gary, the two separate systems should have the capability to be isolated from each other. Very hard to do without a bio filter...

My origins were more to do with backyard aquaculture than aquaponics so bio-filters was always part of my thinking right from the outset.

The proliferation of fishkills attributable to low DO levels and the myths that surrounded the use of grow beds to capture solids simply confirmed my belief that an aquaponics system that had bio-filtration (in addition to the grow beds) was going to be a safer and more productive environment than one that did not.

You will find the K1 will work very effectively as a packed media. If you already have a way to set it up to clean, great!

I thought that I'd just switch the air that is used to "roll" the bio-filter media long enough to stir up the muck in the clarifier prior to draining the watery solids. Not as technically elegant as the Nexus but a whole lot cheaper.

In general all the aspects are there for a great little set up. For the small foot print a bio filter takes and for the safety it provides, it is my opinion all aquaponics should have included as part of their system design. Personally, Gary I would arrange things a little differently but I think what you are doing is just great.

Thank you.

I still think I can do better. I'd like to get more water going through the system, largely (as I said in another thread) so that I have some capacity to 'sweep' the solids on the bottom of the fish tank toward the outlet pipe.

Gary

[Crusty]

The proliferation of fishkills attributable to low DO levels and the myths that surrounded the use of grow beds to capture solids simply confirmed my belief that an aquaponics system that had bio-filtration (in addition to the grow beds) was going to be a safer and more productive environment than one that did not.

I was really surprised that biofilters were not common practice. I understand the grow beds have some capacity and it really is dependent on the amount of fish one is keeping in their tanks, but how does anyone know what that capacity if they are not using the kinds of formula I exampled previously. Just the same I would be installing one just for the pure safety of it.

I thought that I'd just switch the air that is used to "roll" the bio-filter media long enough to stir up the muck in the clarifier prior to draining the watery solids. Not as technically elegant as the Nexus but a whole lot cheaper.

mmmm I see no major issues with it. The nexus "upwells" through the packed media though which makes it more efficient the more blocked it becomes. I could modify it for you to work like a nexus but I am sure the journey is part of the joy of backyarding.

I still think I can do better. I'd like to get more water going through the system, largely (as I said in another thread) so that I have some capacity to 'sweep' the solids on the bottom of the fish tank toward the outlet pipe.

I suppose incorporating a center drain (not through the bottom), doubling as a skimmer box would work well enough as long as the inlet was designed to "spin" the tank.... Not sure if that made sense, it makes sense in my head. Something very easy to do, this would fix any solids removal in the tank.

Food for thought...

[GaryD]

Hi,

The plants in our Baby Q grow bed are four weeks old this week......and the system has provided its first dividend. We harvested coriander and a couple of lettuce.

Our most recent batch of solids were digested. The photo illustrates what happens if you leave the digested solids to settle for too long. The floating material is particulate matter that has been digested but still has enough gas in it to cause it to float.

In wastewater treatment circles, this is called 'bulking' and it's not generally something that engineers much care for.

Gary