Biofilter bag


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I have a question that either is obvious to folks here or weird, I don't know. I have a bag of lava rocks and another full of spongy biofilter stuff in my main waterfall at the head of my stream. The pond stays clear, but the waterfall and stream got bad algae this summer, so I know I need more filtration.

I have a second waterfall, but it doesn't really lend itself to adding bags of filtration material, but then I wondered: do these bags of biostuff need to be in waterfalls at all? It's the only place I've ever heard of them other than external filters, and those two things have water flow in common. And yet, it's not obvious to me that water flow should add anything special such that the biofiltration won't work without it. My understanding is that these things work because they host beneficial bacteria, and I don't know why moving water matters for them to do what they do. I have some places in my pond where I can easily place pretty good sized bags of biofiltration material inconspicuously and would like to do so if it would work.

I actually got an external filtration system for my second waterfall but haven't hooked it up, because I've been travelling for extended stretches in the summers lately, and I don't want to leave that responsibility to others. Too much can go wrong, too horribly, when I am away, so I'd rather keep that untouched until these travel trips ease up a bit in a few years, or at least only run it when I'm here. Hence my thinking about the bags in the pond. Has anyone here ever done that? My fish are only getting bigger, and I can't get rid of a recent explosion of uninvited snails in the stream, which I think are contributing mightily to the problem, so this is not a problem that is likely to go away on its own. Plants can only do so much. Thanks in advance!
 
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JRS

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The nitrifying bacteria that break down the fish waste require oxygen so they will grow all throughout the system on any surface but highest concentration and thus the most efficient waste reduction will be on large surface areas (filter media) with abundant supply of oxygen (water flow). You can still get algae in a well filtered system. Other compounds such as nitrates, (the end of the nitrogen cycle) and phosphates can lead to algae blooms. You might consider a UV sterilizer for suspended algae or a bog filter to use up nutrients for all types of algae.
 
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Jhn

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Do you rinse all the gunk of the bags regularly, if not those things can become nitrate factories and contribute to algae problems if there aren’t enough plants and the right types in the pond. Also, the snail explosion is more than likely in response to the excess algae not the other way around.

Personally, I removed all the bags of filter media from my filter system years ago, for the aforementioned reason and as JRS said bacteria will colonize every available surface in the pond. Also, my pond is heavily planted and has a bog filter, so in my case it was completely unnecessary and even counterproductive to have the filter media in the pond in general.
 

mrsclem

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Just having bags of filter media in the pond poses a problem when you need to clean it. By just having it loose in the pond, the gunk will just fall off when you remove the bags and go right back into the pond. That's why they are used in external filters. You shut the filter down, remove the media, rinse and replace. If you decide to go with your external filter, it needs to run 24/7. Consider a bog, best filter system for the money and maintenance free.
 
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I'm going to suggest you consider less filter media and more plants. Plant your filter and ditch the bags of stuff you have to clean. More plants in the pond will help take up all the excess nutrients that are currently feeding the algae. And don't discount the algae as a helper in your pond - it's doing a job too in helping to keep your pond clear and your water healthy for fish! Algae often gets a bad rap - it's just a sign that you're a bit out of balance.
 
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Thank you all for your tips and insight. I'm maxed out on plants--there's nowhere left to put any, nor a bog. I have floaters in the waterfall and the stream is fully planted; I spend a lot of time during the growing months trying to manage my out of control plants, actually. This fall I finally decided to get rid of the pickerel rush. It just got to be too much; I will replace it this Spring, but with something less domineering. I understand pickerel rush is good at removing nutrients from the water, but its endlessly recycling stems/leaves/flowers seem pretty steadily to add to that nutrient load, too. I have been remiss in cleaning the media bags in the waterfall, however, so I'll start there.

Fortunately, my set-up is extremely well oxygenated. I have the main stream/waterfall, the secondary waterfall, which is fairly significant, a tertiary waterfall that is kind of an offshoot of the first one, plus an aerator with four air stones. If I do add the media bag to the pond (which I now understand to be possible but not necessarily a great choice), I'll put it adjacent to one of those air stones. But for now, I'll start with taking care of the ones I've already got in the main waterfall. Also, I didn't add the snails, and while I know they feed on the algae, they also die and their numbers are pretty explosive. Al those snail carcasses have to be feeding the problem. I'd love to get rid of them.

Fortunately the algae has been mostly concentrated in the waterfalls and stream. The pond is always crystal clear. This is the first year algae has been a problem, so I'm hoping to avoid a repeat next year. Thanks again for the help, everyone.
 
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sissy

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Filtration is great but I found that the best thing is tons of aeration in the water .I have the waterfall spitter I made and it had lots of bubbles of air and since I built it the water fall pond and rocks have been clean of algae .Plus I never have much time to feed the fish so that may help a lot also .This is a week ago when I took all the plants out and had to clean out the pipes from the filter tank after I pulled the plants and the junk clogged them .Really did nothing else
100_8613.JPG
 

cas

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I use to have those bags full of the spongy filter stuff in my biofalls too. I replaced those media bags with two Matala 24” round, 6” thick, green filters in 2016. These two filters add 300 SSA (specific surface area) in the summer. 1 SSA will convert 1 mg of Ammonia per day. I need that extra SSA because of the size of my pond (small) and the size of my fish (getting bigger!).
These matala filters are easier to clean than those spongy filters and I only clean them at the end of the pond season. Below is a picture of the round Matala filters. The different colors are different densitys. I am using the green which isn't the most dense but I didn't want it to clog.

1574507245705.png


 

cas

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Here is a picture of the round filters in my biofalls. I used some of the spongy filters along the sides at the top since the biofalls box flared out at the top.

Biofalls filters.JPG
 
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Fortunately the algae has been mostly concentrated in the waterfalls and stream. The pond is always crystal clear. This is the first year algae has been a problem, so I'm hoping to avoid a repeat next year.
String algae does love moving water. Our waterfall will sometimes get overgrown with string algae both spring and fall - anytime the plants are either not yet growing or done for the season. I usually leave it and see what happens once the plants get going. I remove it manually while I'm waiting for things to balance out, but if it doesn't get under control, I'll use some sodium percarbonate to get rid of it completely. Simple, safe and very, very effective. People also use hydrogen peroxide for this reason, but I find the SP to be easier and quicker to use.
 

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