Filtration Advice Please

[Hawthy]

Hi. First time here. Looking forward to learning and sharing.

We live in Brisbane, Australia. Sub-tropical climate where in winter we see very little rain but it can get down to almost freezing (say 2 or 3 degrees Celsius on a clear night but back to 24 degrees in the daytime - lucky us, I know) and can be very hot in summer (up to 40 degrees Celsius with high humidity and sometimes heavy rain - maybe not so lucky).

We have two ponds. Both are probably 40 years old. Made of concrete. Each are about 1.5m by 2m with a depth between 45cm and 60 cm. We had goldfish in both and gave them no care for years. (Please don't alert the RSPCA). We decided to do the ponds up.

We took all the goldfish out of Pond A and moved them to Pond B. Then we completely emptied Pond A and shovelled out everything on the bottom. We scraped off all of the soft concrete from the sides. We repainted with a pond sealant from a popular hardware chain and refilled after allowing the paint to cure for a few weeks.

We let the water in the pond sit for a couple of weeks before transferring the goldfish (about 60 or so) from Pond B back to Pond A. We had saved one papyrus plant and a small water lily
.
The water looked ok for a few days. Then we took a two week holiday and left the neighbours to feed the fish. I am not entirely convinced that the kids next door didn't overfeed but it was free service, so we can't complain.

The water when we returned was green and murky. We emptied a third of the pond and refilled from a rainwater tank. I bought a Pondmax Ev2900 pump with a fountain. After a couple of days, the water looks clearer (though not clear) and the fish are clearly entertained by the fountain. I added another water lily today and some other leafy water plant that sits 2-3cm below the waterline and is apparently an "oxegenator".

My question is, when I refill the other pond and transfer half the fish (30 or so goldfish) back into it, should I get gravity fed filters for both ponds, or will the fountain pumps and plants be sufficient?

 

[Mmathis]

Hello and welcome! Your climate sounds a lot like mine here in Louisiana, USA!

I think what happened with your first pond was that by cleaning it so thoroughly, you destroyed all of the beneficial bacteria. Letting the water sit for weeks does nothing to establish the beneficial bacteria. The beneficial bacteria colonizers on surfaces, like walls, gravel, rocks... You need the fish to be in the water to establish the BB. So basically, your pond has started a new cycle and you have new pond syndrome. On your next pond, adding 60 or so fish at one time is a little much, but you could add a few at a time and monitor your “cycle” with a water test kit. Once the ammonia and nitrites begin to drop, add a few more fish, etc.

You can never have too much filtration! And you can never have too many plants! I am not familiar with the Pondmax system. We are big advocates of natural filtration, AKA bog filters (wetlands filters or eco filters) — you might want to look into that, depending on the amount of room you have to work with. Bogs can be made using containers, or they can be a part of your pond. You say both of your ponds are about the same size 18 - 24 inches deep, and about 4 ft x 6 feet (hope I converted that correctly).

 

[j.w]

@Hawthy

 

[Phaewryn]

Sounds like to scrubbed all the beneficial bacteria out and then put in far too many fish and got an algae bloom because you had nowhere near enough plants to deal with the excessive nutrients from that massive fish load in an uncycled pond. I'd say you are lucky no fish have died so far and you should count your blessings. Have you tested the water conditions? You have 60 goldfish (although you don't say what size they are I'm going to assume quite large since you said they have been just doing their thing for years) in 1350 litres (357 US gallons). That's a lot of fish for that volume of water, even in good water conditions, and you threw them into a uncycled, non-vegetated, sterile wasteland. You need about 20-50 more plants (enough to cover a third of the water's surface area) and about half the fish to make that sustainable. I wouldn't be so quick to blame it on the neighbor's kids overfeeding: what you did would cause the problems you have with no feeding at all. Your filtration is not going to resolve your problem. You need a lot more plants and a lot more patience, and some beneficial bacteria. If you plan to do the same thing to the other pond, expect the same results (or worse). My advice is to not do pond B at all, put all but 10 the fish back in the healthy pond (the one you think of as dirty/old/unmaintained), move about 1/4 of pond B's good cycled water over to the depleted uncycled pond A in the hope that the beneficial bacteria will colonize pond A, and wait til pond A cycles and has enough well-established plants to support it before doing anything to pond B. It will likely be an entire year before you can do the other pond safely since you have no plants established in the refurbished pond now and plants are essential when you have that many fish to deal with.

 

[Hawthy]

Thanks for your help everyone. That sounds like a plan, Phaewryn - except that we had already emptied pond B before I thought to look at this forum.
I have bought a few more plants and put in some booster balls (apparently a probiotic for ponds) and put in a little barley extract. The fish seem quite happy and the water is clearing up slowly.
Introducing the fish a few at a time to the second pond makes sense. I successfully kept aquariums with Discus and other fish for years and understand the need to populate tanks gradually. It was just a little difficult when our six original goldfish multiplied to more than 60 and we decided to empty one pond. We had nowhere else to put them.
Any thoughts on the benefits of a large pre-filter sponge about 300mm x 120mm x 120mm (or 12 inches by 5 inches by 5 inches on the old scale)? The pump moves about 3000 litres per hour, which is about the volume of the pond. I am hoping that the pre-filter will catch and hold stuff to accelerate the growth of the good bacteria.

 

[Jhn]

Thanks for your help everyone. That sounds like a plan, Phaewryn - except that we had already emptied pond B before I thought to look at this forum.
I have bought a few more plants and put in some booster balls (apparently a probiotic for ponds) and put in a little barley extract. The fish seem quite happy and the water is clearing up slowly.
Introducing the fish a few at a time to the second pond makes sense. I successfully kept aquariums with Discus and other fish for years and understand the need to populate tanks gradually. It was just a little difficult when our six original goldfish multiplied to more than 60 and we decided to empty one pond. We had nowhere else to put them.
Any thoughts on the benefits of a large pre-filter sponge about 300mm x 120mm x 120mm (or 12 inches by 5 inches by 5 inches on the old scale)? The pump moves about 3000 litres per hour, which is about the volume of the pond. I am hoping that the pre-filter will catch and hold stuff to accelerate the growth of the good bacteria.

You want your filter system/pump to turnover your ponds twice per hour on one as small as yours. The sponge prefilter will get populated with bacteria, as beneficial bacteria will populate every wet surface in your pond, as Mmathis mentioned.

It wouldn’t hurt to add some type of gravity fed filter that dumps back into the pond, along with adding more plants. You could even use some type of stock tank (not galvanized)to create a bog filter that would gravity feed back into the pond. It is important to know which plants to add, while all are beneficial to the health of your pond some are better than others. You want plants that spread quickly and are easy to weed back like water forgetmenot, water cress, water celery. creeping Jenny and irises do well too but they can take abit to get going. Lilies while looking nice and providing shade don’t really consume as much nutrients from the water especially when potted. Adding a bunch of plants have an added benefit in new ponds as they can lessen the severity of the cycling process of the pond Consuming the by product of the fish waste especially the ammonia and nitrates.

 

[addy1]

Welcome to our forum!

All good advice up there ^^^^^^^^^^^^^^

 

[poconojoe]

Agree with all.

Too late now, but next time save some of the "old" water to help get the sterilized pond going.

It's not usually a good idea to empty and clean out a pond in general, but in your case I understand why you did it.

 

[Hawthy]

Thanks again for your advice. A lot of the plants that do well in North America do overly well in Australia and are considered weeds. They're pretty much not available here to buy. I thank you all for your valuable advice. If the ponds wind up looking good, I will post a couple of pics. Thanks all.