Backyard Aquaponics
A place to discuss aquaponics

hi everyone!

1. i already have a pump pumping water from sump to my aquarium. can my homemade pvc overflow pump the aquarium water up to my growbed or do i need a second pump to do this?
2. do i still need to use an aquarium filter if i have sump filter? do i even need a sump filter? does the growbed acts like a filter?
3. do i need a undergravel filter?

1. Based on your slightly ambiguous information. Yes, you should be able to add the growbed into your current water cycle. You don't need another pump, but it could provide redundancy.
2. Additional filtration is usually not a bad thing. The growbed acts a both a solids and biological filter, but since you already have your aquarium filtration in place I would leave it in the system. You may wish to go through the growbed first, using it for solids and sump filter primarily for biological, or visa versa. I would personally put the water through the sump filter first.
3. No. Unless you are unable to easily clear the fish waste from the bottom if the tank and get it into the filtration....then probably yes. If you are running a weir you can probably create a solids lift overflow by installing an additional layer of glass/plastic/quater pipe around the entire weir wall, but with a gap at the bottom. This should draw the crap up between the new layer of plastic and the weir, before existing over the top of the weir

If you are going to run an undergravel in a sump system and you don't want to modify the overflow, it might be worth looking into a reverse undergravel system. It uses a reversed powerhead instead of an airstone and will give you the biofiltration of the gravel bed without trapping a load of fish waste underneath. I can't see as you would need it though, especially if your sump is set up with biomedia.

There's no benefit in anyway... to run "undergravel" filtration in an AP fish tank.. reverse or otherwise...

Use your grow beds.. and/or exernal filtration... keep your fish tank clean and clear...

Ohh ya, Based on your slightly ambiguous information.

Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere.

Wouldn't there be benefit in getting solid waste out of the tank substrate (assuming it is a traditional tank setup with 2-5mm gravel @1-2" deep) and into the AP system so it could be utilised by the plants?

I can't see it being necessary for biofiltration, although that would be a nice side effect, but the circulation in a rectangular overflow/sump system is woefully low by AP standards and even if you increased it, you would still have slow flow or even dead areas due to the shape, and difficulty keeping the solids out of the substrate. A lot of the time aquarium people just use RUGF to modify flow patterns and reduce maintenance by keeping the solids moving until they get picked up by the main filter.

It seemed like the idea of getting solid waste out of the tank and into the sump would transfer nicely to AP. Adding an RUGF would be a cheap and effective way of doing that.

It would seem simpler to avoid the problem of substrate altogether. Paint the outside base black, add a few rocks for territory markers & Bob's your uncle

Exactly... there's just no need.. or benefit in having a substrate in an AP system... but some major downsides...

AP systems are RAS aquaculture systems.. not aquaria...

True

There are some major downsides in aquaria too, and I'd hazard a guess they are quite similar. Unfortunately it serves as one of the the main substrates for nitrifying bacteria in a fully stocked tank, especially those that are overstocked or don't have a wet/dry sump, and some ornamentals are fond of the stuff, so we're kind of stuck with it :/

In.. what would you call it, an aquaponic retrofit for an existing display tank? In that case, I suppose it isn't really one thing or another. Is there a word for that specific type of setup? The existing aquarium + growbed arrangement?

There's nothing wrong with adding a grow bed to an existing aquarium... for extra filtration... and to grow a few plants...

And it would certainly help lower your nitrate levels... and cut down the need for maintenance.. and water changes.. to some degree...

@callatya

Yes. My comment in answer 3 regarding the modification of the weir was in leu of using any substraight and undergravel filter. I.e I was proposing a solution to remove solids from the base of the tank, in the absence of substraight, as opposed to trying to filter it through some type of substraight.