Freshwater Sump / Refugium

[jjohnwm]

Lol, this thread takes me back to my undergravel filter days; I "knew"...thanks to TFH and other high-falootin' sources...that my 10 gallon pride and joy was on the cutting edge of filtration technology.

A few decades of DIY filter designs, a decade or so with marine tanks using (gasp!) reverse-flow UG filters (home-made by me, because of course I "knew" I could do it better...), a few decades more of sumps and Mattenfilters and Vortex diatom filters... and it eventually became apparent that these innovations don't make our aquariums healthier, but they sure make it easier to keep them healthy. But that doesn't mean less time spent on tanks, it just means more tanks can be kept properly in the same amount of time. And with each new innovation and development, we just knew that we now had it made...

Never forget that great line spoken by Tommy Lee Jones in "Men In Black":

A thousand years ago, everybody knew the Earth was the center of the universe. Five hundred years ago, they knew the Earth was flat. Fifteen minutes ago, you knew we humans were alone on it. Imagine what you'll know tomorrow.​

 

[thiswasgone]

Gotcha...

Triamond said, " However, the filter is also supposed to degrade uneaten and undigested food and feces into CO2, NH3, etc. This is the role of heterotrophic bacteria/archaea. Much more space is required (20-100 times), as this process is more complex."

That didn't make sense to me. Specifically, the bacteria that breaks down the physical waste, would exist on the physical waste, wouldn't it? I don't understand how bacteria on the front glass, or on a rock in the aquarium, will break down physical waste that got picked up in the filter. That said, I do understand that once the physical waste is broken down into it's chemical components, the bacteria on the glass or a rock will consume those chemical compounds, as they are then in the water column.

You gave a beautiful description of how most bacterial colonies exist and evolve in our aquariums.

_____________________________________

This thread has gotten fairly complex, and I thank all of you who contributed to that.

I have decided to abandon the the sand as filter media... It's a choke point in the sump and I don't have a plan of how to clean the sand. It seems much more practical to stage sponges in that chamber. I'll likely get several grades of density and play with different combinations.

Getting rid of the sand as filter media also allows me to modify that last chamber and lower the pump to the bottom of the sump, as suggested here.

You've also shown that terrestrial plants are more efficient at consuming nitrates, phosphates, etc than aquatic plants. So I'll abandon the soil & sand from the refugium chamber. I have a ton of Pothos and Wandering Jew that has propagated water roots. I will anchor them in the refugium section and let them grow out of the sump.

I understand I won't grow enough plants between the aquarium and the sump/refugium to remove 100% of the waste, but I'm quite convinced it will help. I'm also not convinced there is anything else that would be a more productive use of that space. I'm still baffled that even though we've thoroughly discussed that this system, like most systems, will have more than enough surface area to host suitable quantities of bacteria without Bio-Media, yet it's still being suggest to add Bio-Media.

I'm also still interested in the simple "algae scrubber" idea, but replacing algae with Java Moss. Even if it doesn't do much for the aquarium, having a little built in Java Moss farm could be an asset in it's own right.


Thanks again to everyone who contributed here. And feel free to further critique or expand on what's already been said.

Don't get totally discouraged plants definitely help but the exact mechanisms can get a bit complicated if you're trying to math your way out an exact solution. In short, more plants = more nutrients removed but don't expect it to completely remove the need to avoid doing water changes in any monster fish keeping endeavors unless you have an aquaponic garden ready haha.

Also, efficiency isn't the end-all-be-all in relation to fish keeping. While mathematically a MBBR is the most efficient biological filter it doesn't mean it's the most convenient and that's what this all boils down to. When I had no space and small tanks I used HOBs, when I had no space and large tanks I ran canisters, and now I have both I run sumps and a MBBR. Just find a system that works for you and stick to it so long as there isn't any problems with your water parameters; less work on equipment is more time looking at fish . There will probably be a bunch of trial and errors along the way but I doubt anyone on this forum or any other will claim to have made 0 mistakes when raising fish especially when trying to implement a DIY solution.

 

[triamond]

Toby_H
If the aim is to reduce the necessity of changing water, another option is to use nitrate-selective ion exchange resin (Purolite A520E, PureResin PA202), provided you can purchase reasonable quantities. These resins bind nitrates (and phosphates if regenerated frequently) and also remove dissolved organic carbon (DOC). Most people without over-filtration can observe a 'stunning clarification of water' when they add the resin to their filter. It is easy and cheap to regenerate with salt for water softeners—simply soak it in a bucket with a salt solution for several hours. One liter of resin can hold 20-40 grams of nitrates, so a few liters should suffice. The resin is quite durable but can be prone to 'organic fouling' and may lose capacity over time.

 

[cockroach]

This is why I'm struggling to wrap my head around the suggestion of adding bio-media instead of a refugium. I accept the sized refugium I'm working with will not remove the need/benefit of water changes, but it will reduce the nitrate/phosphate/other build up. My goal is not to remove the need for water changes, it is to reduce the waste build up between regular weekly water changes.

As I see it, these do not have to be separate.
My centre area in my 55gal sump is a little over half filled with plastic bio-media. I laid a grate on top of that and placed extra, larger, ceramic media. Then between that all grows pothos. roots trail down between media unchecked and the plant grows across and out of the sump.
other epiphytes like anubius and java moss go in their too. And some emersed terrestrial plants in terracotta pots.
So I have media and a refugium.

 

[Toby_H]

Toby_H
If the aim is to reduce the necessity of changing water, another option is to use nitrate-selective ion exchange resin (Purolite A520E, PureResin PA202), provided you can purchase reasonable quantities. These resins bind nitrates (and phosphates if regenerated frequently) and also remove dissolved organic carbon (DOC). Most people without over-filtration can observe a 'stunning clarification of water' when they add the resin to their filter. It is easy and cheap to regenerate with salt for water softeners—simply soak it in a bucket with a salt solution for several hours. One liter of resin can hold 20-40 grams of nitrates, so a few liters should suffice. The resin is quite durable but can be prone to 'organic fouling' and may lose capacity over time.

Only $531 on Amazon, but free shipping!

lol... that's for 44 lbs. Clearly this will be an expensive option but I won't need 44 lbs.
Like the refugium, I wouldn't want to lean on something like this to "remove" the need for water changes. But if it works as simply as you suggest and I can locate small quantities, it may be worth adding to "reduce" the frequency of necessary water changes.

I'll look into it more. Thanks for the tip.

Amazon.com

 

[Toby_H]

Okay, based on this conversation and other exploration, I've made some modifications... Same general concept, but modified details.

Color Code...
light blue is air
darker blue is water
yellow/gold is sponges
pink (bottom left) is biomedia, whatever rings, balls, scrubbies, etc I have laying around
lavender (bottom right) filter floss / quilt batting / water polishing media

I've scrapped the concrete board for the inserts. I'm using corrugated plastic, which is basically plastic cardboard. Check it out on Amazon if curious. I bought 2'x3' sheets. I've worked with it before. Silicone works well on it. The walls of the baffles were thinnned in the diagram to reflect this.

The walls of the Left baffle/box extend well above the top of the sump. This is because the sponges will create some amount of resistance. There will be an overflow notch on the refugium side. If the sponges cause too much resistance and the water level gets too high, the water will overflow through that notch into the refugium bypassing the sponges.
The 90 gal is set up now and I'm making the baffle boxes this weekend. I'll be setting them up and toying with flow/resistance well before it's put under the tank.

"dirty" water flows into the first baffle, through the sponge (yellow/gold). The sponge will be a layers of different ppi foam blocks. I've gotten a bunch of 2" thick pieces from 20ppi to 60ppi to tinker with.

Bio media (pink) is next. As discussed, I'm not big on biomedia as bacteria will live anywhere and everywhere. I don't think I need it, but this chamber would otherwise be empty so why not add it.

Water is then released to the refugium. I removed the soil/sand as substrate. I'll primarily rely on Pothos and Wandering Jew. You guys proved that terrestrial plants grow faster and consume more waste than aquatic plants. That said, I'll still stick some aquatic plants in here but more to cultivate the plant than to increase waste removal.

Not shown... I'm still considering adding the "algae scrubber" I posted previously, though housing Java Moss instead of algae. Again, I do not think this would make any tangible improvement to the water quality, but large wads of Java Moss have trade value in my Local Fish Club. So if I could put together a Java Moss Farm relatively cheap, it would be of value to me outside of filtration.

Water flows through the (green) refugium... then through more sponges (yellow/gold)... The pump has been lowered to the floor of the sump... The pump will be wrapped in polishing media... Note: The wall between the refugium and the pump chamber will be at least an inch lower than the top of the sump. This way if the sponges to the right clog and gain resistance, water can overflow from the refugium to the sump, bypassing sponges, before the pump runs dry or the sump overflows. Again, I'll be tinkering with details on this to ensure the wall is low enough to in fact provide this protection.

Not shown... I'm still considering a UV on the return line. This sump will be on a Discus tank, so every little bit I can do for water clarity and removal of free floating bacteria will help.

I have the left baffle/box made waiting for silicone to cure. I'll make the right tonight and tomorrow. They'll be installed in the 90 gal mid week and I'll start pumping water from right to left. The tank is a mess as it is. Bare bottom, minimal decor. 3 Fish that just didn't fit anywhere else. The greenest water I've ever had in an aquarium (algae). I'll put Potos in it too (I have a ton in another tank) and let the Pothos battle the algae. I could water change it away but it'll be an interesting experiment to watch them battle for dominance. Or it won't be and I'll water change it away.

Input still welcome. It'll be a work in progress for at least a couple more months, more likely a couple decades.