Plant filtration and winter

[Spartamets]

My winterization question pertains to my reliance on plants for filtration and what it will mean to lose it. I intend to add pictures to clarify, but this is the basic situation. I have a waterfall with biofiltration, a stream of 15 feet or so that is filled with small rocks/pebbles, and a skimmer filter. That is the non-plant-based filtration for my pond, which is about 16x12; it is mostly about 1 1/2 feet deep, probably 2 feet at the deepest, with a plating shelf that extends perhaps 18 inches in the back where the water is maybe a foot deep. So the volume is not huge.

I have 3 koi and a passel of horny goldfish. I started the season (post-heron) with one fantail, two comets, three shubunkin, and four orfe. Those fish, including the koi, are reasonably close to fully grown at this point. Over the summer, perhaps 40 new babies were produced, starting in June and continuing through September. They vary in size based on when they were born, but they probably average maybe 3 inches in length. I know that my non-plant filtration is not sufficient to keep up with this amount of fish. I've let the plants do all the work, and I've usually been more "generous" than I otherwise would be in letting the parrot feather, water hyacinth, etc. grow due to the filtration they provide. Everything seems in perfect balance, with crystal clear water and happy fish and absurd levels of plant growth.

But winter is coming, and plants die in the winter. Much of my most significant filtering is coming from bacopa and hyacinths, which won't come back, and which will take some time to grow to "useful" levels (for filtering purposes) after the Spring starts after I buy replacements, at least based on my observations this year of when they started taking off. This leaves me thinking that after the plants die off this winter, my pond will be in a dangerous place until maybe June, when the plants are fully back to speed as it were. Among the perennials that will be ready to grow again once the season starts are parrot feather, pickerel rush, a couple of lily plants and a range of other rushes. At some point next year I will add a pressure filter system/additional waterfall (I have it all already), but I don't expect to have the time to put it together until June, which is late for these purposes.

My question is this: Is my pond doomed?

 

[sissy]

reason I over winter plants in my basement is an early start .I live in a rural area and the garden center I use takes my extra over winter plants for trade of plants I want .Never doomed just goes into a rest period for next year .Just like grass grows all summer but takes a rest all winter so does a pond .As long as you keep an opening in the ice you are OK

 

[Meyer Jordan]

Keep in mind that as temperatures drop so does the Ammonia production by fish due to their slowing metabolism.
The arrival of Spring, however, may bring problems. With your present fish load, you are likely pushing the limits of the pond's support ability. Under these circumstances you can count on a quite heavy algae bloom (pea soup) come Spring. This is good as it may reduce the fish mortality rate that will likely occur.
In the meantime, I would suggest that you actively try to re-home some of the fish.

A note about plants and nutrient uptake- Nutrient assimilation by plants is mostly accomplished during periods of active growth (Spring/Early Summer). As plant growth slows, so does the need for nutrients so uptake is minimal.

 

[Spartamets]

Thank you. I've rehomed 4 fish so far. I *might* be able to move out another 20 or 25 before winter. It seems likely that I will be able to do so in the Spring if it can't happen this Fall (I'd rather not stress them all out with the catching process--especially for 20 fish--during the winter). There is also a resident bullfrog that I hope picks off a handful every year. Interesting about the plants not uptaking as many nutrients when not actively growing. Seems I'd be better off pruning aggressively to encourage continual new growth rather than just letting them grow as I mostly did this year, though the WH often gave me no choice. Fortunately, this year, summer pretty much kept stretching out until about a week ago here.

After I add the pressure filter, which will be serviced by a 2200gph pump (the appropriate size, to give an indication of the filter's processing capability), how many fish will I safely be able to maintain during these plantless intervals? I should be able to rehome a lot of fish every year, and I'm hoping none of the young ones turn out to be koi, but my fantail kept spitting out new batches of babies, all summer long. I'd be tempted to give it away to stop that process, but it's a cool looking fish and I figure at this point there are probably other spawners swimming around, too.

 

[Lisak1]

Your question is a hard one to answer with real specificity. The answer I always give to "how many fish should I have" is "a few less". Unfortunately the way people figure out they've tipped the balance is when bad things start to happen.

You're in a warmer zone than we are, and like you we depend solely on plants for filtration. One thing I do to address the need for early growth is to have plants in the pond that like the colder weather. Marsh marigold will grow through the ice - it's the first thing that grows and blooms in the spring. Watercress loves running water and flourishes in cooler weather - you could grow it in your stream very easily starting right after the last frost. I buy a small bunch in the produce section in late March (doesn't even have roots - just the leaves and stems) and stick sprigs of it in my waterfall and grow literal bushels of watercress all year long. It's one of the best filtration plants you can grow in moving water. Forget-me-nots is another great one that starts early and grows all season long. I also will pull my lilies closer to the surface once the weather starts to warm up - they will start to grow much faster in the shallower water.

Hope that helps! Like @Meyer Jordan said - work on reducing your fish load. The gold fish aren't really as big of a concern as the koi, if you're worried about fish load.

 

[Spartamets]

Your question is a hard one to answer with real specificity. The answer I always give to "how many fish should I have" is "a few less". Unfortunately the way people figure out they've tipped the balance is when bad things start to happen.

You're in a warmer zone than we are, and like you we depend solely on plants for filtration. One thing I do to address the need for early growth is to have plants in the pond that like the colder weather. Marsh marigold will grow through the ice - it's the first thing that grows and blooms in the spring. Watercress loves running water and flourishes in cooler weather - you could grow it in your stream very easily starting right after the last frost. I buy a small bunch in the produce section in late March (doesn't even have roots - just the leaves and stems) and stick sprigs of it in my waterfall and grow literal bushels of watercress all year long. It's one of the best filtration plants you can grow in moving water. Forget-me-nots is another great one that starts early and grows all season long. I also will pull my lilies closer to the surface once the weather starts to warm up - they will start to grow much faster in the shallower water.

Hope that helps! Like @Meyer Jordan said - work on reducing your fish load. The gold fish aren't really as big of a concern as the koi, if you're worried about fish load.

Thank you for your helpful answer. You always provide good insight. I don't think my concern is entirely about fish load. It's more about relying on plant for my primary filtration and what to do when that filtration basically turns off for a few months. Given that my goal has always been to use plants to maintain the pond's balance as much as possible, it's kind of silly of me to not previously have given enough thought to the inevitability of winter.

I will use the watercress idea for sure. That seems like the best avenue to take. I can load my stream up with it, so whenever it starts growing again, I will have a lot filtration up and running instantly. I am also putting in the pressure filter next year, which I imagine will make me safe for quite a significant fish load given the filtering I already have. I only put in three koi originally, which by now are pets, so they are not going anywhere. I'm also fairly confident that, once I have the pressure filter running, I can handle all the fish I have, although I don't know if any of the babies are koi (I don't think so), which would change all my calculations. Those would almost certainly have to go

But my currently-in-the-shed pressure filter doesn't help me for this winter and the upcoming spring, hence my concern, which you have helped to allay. By far the majority of my fish right now are "new arrivals" that I hadn't planned on, at least this many this quickly. My neighbor is a landscaper who has a client with multiple ponds; he told me that I can give him as many fish as I want every year, so I should be able to manage the fish load over the long haul. We just have a very hard time coordinating our schedules, and moving that many fish will require some serious time and planning. It probably took 2 hours to catch 4 fish for a local teacher who wanted them for her class. I am thus not confident that we'll move out the fish for his client before winter, when I'd prefer to leave everything be.

 

[Meyer Jordan]

Seems I'd be better off pruning aggressively to encourage continual new growth

Aquatic plants require basically the same care as terrestrial plants. Most plant pruning is done in the Spring to remove old and.or dead foliage. Pruning plants any other time(Fall/Winter) may encourage some minimal new growth but likely, because the plant is already in or entering its Winter dormancy, will only open the plant up to disease.

 

[Lisak1]

Sounds like you have a good plan for your "surprise additions"! It may help to lower your water level when you need to catch fish - give them less space to run!

 

[Gordo33]

Watercress loves running water and flourishes in cooler weather - you could grow it in your stream very easily starting right after the last frost. I

Forget-me-nots is another great one that starts early and grows all season long. I also will pull my lilies closer to the surface once the weather starts to warm up - they will start to grow much faster in the shallower water.

I use plants strictly for filtration and have had the same success as Lisak1 with the plants she mentioned. In addition I have a 100 gal waterfall tub filled with yellow flag iris. They have a heavy root system and begin pushing up foliage in early spring. I also have scattered them in the pond.

 

[Lisak1]

Ah! You caught one I missed @Gordo33 ! My irises are all early starters too - and the root systems are fantastic! I have them in both the bog and the pond.

 

[sissy]

I have taken ponds apart that had iris planted in them and had to pull them out with my truck and a chain and pulled the liners out with them .I learned if I saw an iris I had to take the fish out first and then the chain was always the easiest way to get them out .

 

[qclabrat]

good thread, do I drop in irises now? I was always concerned with starting bulbs in water as I'd imagine they would go bad over the winter

 

[Gordo33]

good thread, do I drop in irises now? I was always concerned with starting bulbs in water as I'd imagine they would go bad over the winter

The iris I started with were established . Started with 12 rhizomes 4 years ago and have multiplied to the point I've lost count.
This the roots after removing the iris from the tub. May 14 2017

This two weeks later back in the 100 gal tub during pond Rebuild

That tub started with a dozen plants 4 yrs ago. Great filter

 

[Gordo33]

@sissy how many years were the iris growing in your pond when you needed the chain saw and truck? I guess I'll keep a closer eye on the ones in the pond

 

[sissy]

It was not my pond ,I took them out for realtors of homes that were foreclosed on .I have taken over 12 ponds out so far and rehomed a lot of fish ,never kept count .Wish I had .One pond was in my neighborhood and now the pond was put in 2013 and I took it out in 2016 .It was not preformed but a liner pond ..The pond was just over 2 feet deep and liner I was able to save most of it after hours of painstaking work of carefully pulling roots and cutting the in small pieces ,I save most of the 20x30 liner but 5 feet of it on one whole side .They had the iris planted near the waterfall side .The root mass took up most of it .I know when they built the pond because they asked me for a little advice .The house was built in 2012 and they bought in December 2012 and put the pond in the next spring .