Backyard Aquaponics
A place to discuss aquaponics

[align=center] This topic discusses the merits of a UGF (Under Gravel Filter) in a DWC system [/align]

Well, almost regular aquarium. The larger gravel overtop the smaller gravel is not standard, but I'm not quite understanding how that would make such a big difference in needing to clean it. (Referencing comments from another thread.)

I will be (almost) patient and let AA continue the story.

LOL You are as patient as I am, you'd think they were on the other side of the world!

Interesting AA, is this correct (my terminology, just trying to get it right in my head):

A false floor is placed on the bottom of the tank (~10mm spacing), area under floor not required to cover all of floor as long as area sufficient to supply pump flow
Floor is made of rigid plastic, not much weight on top so 3mm thick would be okay
Small slits cut into plastic (chainsaw job) to allow water flow
Gravel – 2 different sizes which trap the solids
Pipe attached to be connected to a pump

Solids are broken down as it is pulled through the gravel then is sucked up by the pump and removed…..

You have whetted my appetite, when’s the next installment

Patience patience NOW!

It works automagically

OK, the large gravel to small.

With only small gravel the waste sits atop the gravel and is easily knocked about by fish movement.

With the large stones comes gaps where solids can be trapped and worked upon by bacteria and the suction provided by the pump.

cool, so that may be the secret to success in UGF's of any aquarium. I will try that when I set mine up

The secret is no secret - it's the AP, this is only a part of it so please, no conclusions yet. I have no idea how this works in a conventional Aquarium and would hate to spread disinformation (pet hate)

Sorry Ell you posted as I was so didn't see your post.

- The UGF should cover as much as possible, but I was putting a square peg in a round hole.

Next installment in 5-6 hours I must go chase some serenity I'm a bit jumpy last 24 hours. Long walk by the beach ahhhhhh.

Life is Great!

calm blue ocean...

Hmmm. contemplating, contemplating. Traditionally, I have set up my aquariums with both a UGF and an over-the-back power filter simultaneously. 50mm/2in of >5mm/.25in gravel over the UGF. Given that the fish in my aquariums were generally not monsters, poo worked its way into the small gravel OK. Siphoning once a month sucked it out for disposal. My husband had the monster fish (gigantic plecostamus). Their poo drifted about. YUCK!

AA, I will be interested to know the fishload and total size of the system. I am intrigued.

OK I'm back.

Watched Blackadder 3 last night - the dictionary episode. Baldrick takes C.

C - Big blue wobbly thing what mermaids live in.

That programme is still as funny as ever.

The ocean is certainly calming, and got a bunch of shell too, oysters and all sorts of wee clam shells.

Back to the system - > see next post.

what time of day is it there? It's nearly 1pm in Qld, 2pm in NSW, Vic etc

It's 10:00PM here. Almost bedtime.

The larger gravel would still house the bacteria, but would allow larger waste & Detrietus to be trapped. I had some success using pea gravel in one of my tanks, but it kept raising the PH(around 7.5-8) and I had Tetras in it, (they like 6.3-7.2), so I swapped it for regular aquarium gravel. Makes sense! The smaller gravel would act as a pre-filter for the UG filter.

DWC Recirculating Aquaponics. - The Planters. I have 4 if you're wondering.

I circulate the volume of water in each planter 6 times an hour. Anything from 6-12 planters should have an increased rate of flow (10 times - 12 times per hour) to ensure good aeration in the end planters. I wouldn't go under 5-6 times circulation even with only 2-4 planters. You want constant aeration and good flow to ensure you have no anaerobic conditions. Anaerobic conditions will bring many problems and eventually kill everything.

You could go slower flow and add bubblers, but we're not here (this thread) to discuss what the scientists do with lettuce... Also, I use my solids, hence the heavy aeration requirements, it's not the same thing at all.

Each planter, as you can see in the photos on page one, is a recycled container, placed sideways, with a few holes in it. Buckets, half barrels etc can all be used for this. Lightproof is a pre-requisite for whatever you use for planters. Got white buckets - paint em or wrap them. Let light in your planters you encourage algae which removes nutrients the plants should be getting. The holes...

1. Small hole for water coming in (I've used 13mm piping and 13 mm T's or elbows for water in according to whether planters are on the end or in the middle). Place these holes on top. The water coming in is already aerated, and pushes down into the planter forcing movement and circulation of water and air.

2. Large hole for a netpot (larger netpot is better, we want medium, just not tons of it) I have 8 inch netpots.

3. Medium size hole for passive water return. Passive return should always be at least twice the size of the intake to ensure water drains and does not flood. I'm using 25 mm for return. This third return hole is crucial in it's placement as it determines the water level in the planters. You want 4-6 cm's of dry medium for your plants to form air roots and water roots beneath these. Insufficient air roots causes problems as various root gaurdian type fungi and bacteria live in this zone. I measured 6 cm's down, saw it coincided with my lids, hence the returns I have.

The pump.

Each planter holds 20 litres of water up to the return level. There are 4 planters. I needed 80 litres (4 planters x 20 litres) circulated at least 6 times an hour = 480 lph.

Then, add another third of the flow to compensate for the drag of water down through the UGF, and the venturi attached which aerates the water going to the planters. 480 lph plus 1/3 (160) = 640 lph.

Then there is the head height of the pump. I pump from 30 cm's underground to 45 cm's above ground. Head height = 75 cm's.

I needed a pump that would pump a minimum of 640 lph at a head of .75 metres.

I got a King-2. This baby is only 20 watts, pumps 1000 litres per hour with a max head of 1.95 metres. It does the job well.

To measure the flow of water at a given height simply get a measuring jug, time how long it takes to pump a litre, and do the math.

A venturi is placed on the line going from the pump to the planters. I actually have mine after the UGF and before the pump which I've been told causes cavitation and wear etc on the pump, not had a problem with it, it is not noisy either.

Anyway, this venturi pulls air into the water stream that goes to the planters ensuring the high aeration the planters in this system require.

The return water should have a drop, preferably about 30 cm's, for aerating the fish tank via waterfall effect. I have roughly 25 cm drop and no problems.

Any questions before we get into the fish and plants?.....

not from me! Keep going LOL