Low maintenance planted 75g stocking ideas?

[Luananeko]

I've been running my high light/mid tech (dose ferts and use liquid carbon instead of CO2 injection) 75g planted community tank for the last 5+ years. I like the tank, but the 50% weekly water changes and plant trimmings are getting a bit too time/energy consuming now that I'm pregnant with our first child... Considering how my free time is only going to be more scarce once the baby comes, I think it's time to scale back a bit. In the past I enjoyed having a fairly well stocked tank with lots of variety and color, but lately I've found I enjoy the fewer, larger, more personable fish like my Angelfish and my (recently passed) Red Tail Shark. Ideally, I'd like to drop down to a tank plan that only needs a large water change every 2-4 weeks instead.

My current substrate is a pretty deep sand/eco-complete/gravel mixture and has lots of light hungry stem plants, a red tiger lotus, and two amazon swords. I'd like to swap to straight sand of a minimal depth with driftwood bound plants/rocks, maybe other low tech plants and/or floaters (though they seem to struggle a little with my HOB filter) but am not as familiar with the best options. I do enjoy the tiger lotus and swords, but I'm guessing they need too much light/maintenance to fit in with the new plan, even if I let the tiger lotus float leaves on the surface. I've got a dual T5HO fixture currently, as well as a standard T8 strip light. I'm guessing I'd retire the T5HO and stick to the T8 with a plant bulb.

Based on how much of a tear down the above would take, I think it's easier to take the opportunity to rehome most of my existing stock and swap to something that would be more enjoyable. I love bichirs and have always wanted to keep one, and I love my current Angel, so those two are what I'm working the new stocking list around. I was leaning toward something along the lines of:
1 Polypterus palmas palmas
1 Angelfish (from current stock)
12 Congo Tetras
1 Gourami (likely Opaline or Pearl?)

What do you guys think? Workable plan and/or are there other interesting swaps you'd recommend instead of the Tetras and Gourami? Tips on light/plant combos that meet the low maintenance goal are appreciated too Thanks!

 

[Discusluv]

I think that this plan hinges on a couple of variables that are unknown so it makes it difficult to answer the question.
In a low tech-tank with X many fish and x many plants how can I get away with water changes once a month to 2 x monthly without compromising health of fish?
Hard to say. It would have to be tested.
Nitrate levels would certainly play a big part in this equation... but, so would a factor that is not so easily measured:bacterial load.
There are many types of bacteria in the aquarium that are harmful to fish only when the fish is compromised via environmental stress: i.e: aeromonas, columnaris, pseudomonas bacteria.
Some individual factors to consider:
*Angelfish come from waters with very little organic load, so in order to keep them healthy I would recommend keeping your nitrates below 20ppm.
*Some plants that can take lower light and no CO2: all crypts, some swords, valisneria, (all 3 heavy root-feeders).

Your plan may or may not be successful. Im thinking 2 large (at least 75%) water changes monthly minimum may work. It will depend on a good mix of plants to eliminate some of the accumulating nitrates, low stocking, and a high-quality food ( like New Life Spectrum) that doesn't have a lot of phosphates and fillers to foul water.

 

[Luananeko]

Thanks for the input! I'm not adverse to doing large water changes when I actually do the water changes. I have a python setup so the difference between 50% water change to 75% is just a matter of waiting around for a little longer between swapping the siphon direction. The problem I'm running into right now is that I'm doing largish water changes already (though usually every week) while also having to dose ferts & carbon daily, plus trimming the plants, taking the trimmings to my LFS for credit, etc. I'm not opposed to dropping the planned fish load down too if necessary to improve the success rate. I just don't want to be in a situation like I am now where a missed water change here and there will cause serious algae/water parameter issues.

Food-wise I was planning on alternating between frozen foods and New Life Spectrum pellets/Omega One flakes. That's what I use for my current stock, so that's not much to change.

 

[Discusluv]

With the change to low-tech, the time saved in trimming, algae control, dosing ferts etc... will definitely help you have more time to spend with the baby! Congratulations, by the way.
As far as stocking, maybe you could keep it more of a biotope: add a few more angels and go with some deep-bodied tetras that can take the warmer temperatures that angelfish like such as hyphessobrycon sp. ---- Lemon tetras,Rosy tetras, or Bleeding heart tetras. Or, you could do some larger rummy-nose or cardinals.
Also, could do a group, at least 6, of corydoras that take warmer temps: sterbei, adolphoi, duplicareous, or b. splendens.

 

[Luananeko]

Sadly biotope stocking has never appealed to me. I understand the appeal for others, but I'm picky about what fish I like and what ones I find "boring". A biotope plan would mean filling half the tank with fish that I don't have any interest in, which isn't fair to them or me since an uninteresting tank is more likely to be neglected/forgotten in favor of more pressing priorities... Adding more angels when I already have one adult would be tricky too.

The bichir is a must have as I have always wanted to keep one and want to try something different than the same ol' community tank like it's been running currently (current stock is angel, cherry barbs, cardinals, dwarf chain loaches). Cory cats just never have been very interesting to me for some reason.

 

[Discusluv]

Of course, we all like what we like.

 

[BBradbury]

Hello Lu...

You can add a couple of Chinese evergreen house plants to reduce the work needed to maintain the tank. The plant takes in all forms of nitrogen from the dissolved fish waste and you can simply remove half the tank water every month or so, to replace the minerals the fish use. The tank is open and you need to top off the water in the tank a couple of times a week with treated tap water. Not much else is needed.

B

 

[Luananeko]

Hello Lu...

You can add a couple of Chinese evergreen house plants to reduce the work needed to maintain the tank. The plant takes in all forms of nitrogen from the dissolved fish waste and you can simply remove half the tank water every month or so, to replace the minerals the fish use. The tank is open and you need to top off the water in the tank a couple of times a week with treated tap water. Not much else is needed.

B

Alas, an open top tank is not an option for a couple of reasons... Bichirs are massive escape artists, plus I have 4 cats that would love to try their paws at fishing

I'm not sure the chinese evergreen houseplants would appreciate my kitties either, as 2 of them even try to eat any fake plants that I bring home!

 

[coralbandit]

So called 'predator' fish like the 'poly'[great fish] only need to eat 2 maybe 3 times a week.It is common that people over feed them like a fish say like the congos...
If you limited your stocking to compatible predator fish that could still keep your interest and lighten the load.
Less feedings means less of everything..
I had for my son a poly with a clown knife years ago in a 75g .I ran a sump and fed pretty light and the tank was easy to maintain.

 

[Luananeko]

So called 'predator' fish like the 'poly'[great fish] only need to eat 2 maybe 3 times a week.It is common that people over feed them like a fish say like the congos...
If you limited your stocking to compatible predator fish that could still keep your interest and lighten the load.
Less feedings means less of everything..
I had for my son a poly with a clown knife years ago in a 75g .I ran a sump and fed pretty light and the tank was easy to maintain.

Feeding the tank each day is easy to keep up with, it's the rest of the maintenance that's wearing me out. My main concern with a predator-only tank with no mid/high level swimming fish is that the tank would be fairly inactive other than when the predators are foraging/hunting. I like there to be something going on whenever I look at the tank.

The tank isn't drilled, and managing the sump I have on my 36g tank using HOB overflows has been a bit obnoxious. I'd like to avoid dealing with that hassle on a second tank. From what I've read, Ghost Knifes need 150 gallons when adult, and are notoriously hard to keep alive long term due to finicky eating. They're super cool fish, but I think it's better to pass on one for my 75g since I have nowhere to put it when it grows up.

 

[Caliban07]

You could try a deep sand bed to encourage denitrification.

Apply nutrients to the substrate and use plants with large root systems. Floating plants will help purify the water. Keep a healthy stock of fish and keep light intensity fairly low.

 

[ZxC]

I agree with the floating plants, let them multiply and remove a bunch once in a while, that will physically remove nutrients from the tank, much the same way macro algae in saltwater refugiums work.

 

[Luananeko]

Oooo, I like the deep sand bed idea. Does that work in freshwater tanks like it does in saltwater? My only concern is that I worry I'd accidentally release some toxic gas if I have to mess with the sand for planting, dosing with root tabs, or when a fish digs.

Sounds like the consensus is floating plants are a good plan. I've got both Amazon Frogbit and Water Lettuce in my tanks at the moment, would one be particularly good compared to the other? Probably the water lettuce I'm guessing?

 

[Caliban07]

Oooo, I like the deep sand bed idea. Does that work in freshwater tanks like it does in saltwater? My only concern is that I worry I'd accidentally release some toxic gas if I have to mess with the sand for planting or when a fish digs.

Sounds like the consensus is floating plants are a good plan. I've got both Amazon Frogbit and Water Lettuce in my tanks at the moment, would one be particularly good compared to the other? Probably the water lettuce I'm guessing?

It depends. Most aquarium substrates will have areas of fluctuating redox (levels of oxygen). You will have fluctuating redox levels even at plant roots etc. At a particular low level of dissolved oxygen within the substrate, a suite of microorganisms will develop that have the ability to utilise nitrates as their electron acceptor. In this case the byproduct is nitrogen gas and the level of nitrates will fall.

However, the deeper in to the substrate you go and the less nitrate is available you may find microorganisms that use sulphate as their electron acceptor. The byproduct of which is hydrogen sulphide. Obviously this is extremely toxic. Sometimes you can see this gas as black spots in light sand.

The thing is, as soon as hydrogen sulphide rises and come in to contact with oxygenated aquarium water it reverts back to sulphates fairly rapidly. You may see some bubbles that in reality are fairly harmless to livestock.

You can add burrowing snails if you are worried about hydrogen sulphide build up. Bottom line is if plants are healthy, their surrounding area of the roots (rhizosphere) will oxygenate the area. It will fluctuate though.

When I used a soil substrate I had hydrogen sulphide gas in the substrate (I had a heavy layer of clay too) I know this because when I come to tear the tank down the smell was horrendous. There were also cold spots within the substrate, the thermodynamics of which also play a part in redox potential. I could never smell the hydrogen sulphide in the tank where the substrate was undisturbed.

Anywho, this was the result.



You could also try a plenum. Due to the level of oxygen maintained in the plenum and the thermodynamic properties, this facilities the growth of fulcative heterotrophic anaerobic bacteria which can utilise nitrate. Kevin Novak swears by these but many people (particularly reef keepers) prefer the deep sand bed. Either way I think as the level of organic matter and mulm accumulates in the average aquarium substrate you will get areas that act just like a plenum. Fluctuating redox can also increase the availability of certain nutrients such as iron.

It is no coincidence that some of the longer running tanks with substrates containing high levels of organic matter and humus are the most stable and plant friendly. They also have some of the cleanest water and can become pretty ‘hands off’ in terms of water changes. I would easily go 3 weeks in my soil tank before a water change.

In the beginning, because I used a soil chock full of artificial fertilisers and the tank lacked these biologically robust features I had massive algae issues.

If I’d have used a floating plant initially and some fast growing stems I may have been able to avoid such a dark period in the tanks timeline.....

 

[Luananeko]

Wow, that's lots of super helpful info! Thanks! I like the DSB idea better than a plenum. Populating it with mulm & nutrients will be pretty easy since the tank has been running for many years so there will naturally be a good amount in there when I'm swapping the substrate around

How deep a sand bed would you recommend? I found the following article that goes into pretty good detail about how to set one up, but they only recommend 3 inches of sand.
Deep Sand Beds

If memory serves I believe most saltwater DSBs are 6+ inches... Is 3 inches really deep enough to accomplish the denitrification goal?

 

[Caliban07]

Wow, that's lots of super helpful info! Thanks! I like the DSB idea better than a plenum. Populating it with mulm & nutrients will be pretty easy since the tank has been running for many years so there will naturally be a good amount in there when I'm swapping the substrate around

How deep a sand bed would you recommend? I found the following article that goes into pretty good detail about how to set one up, but they only recommend 3 inches of sand.
Deep Sand Beds

If memory serves I believe most saltwater DSBs are 6+ inches... Is 3 inches really deep enough to accomplish the denitrification goal?

No problem.

I don’t know to be honest. I haven’t tried a deep sand bed. Like I said you may not need a deep substrate in particular to encourage denitrification. An aged substrate with lots of mulm will eventually contain low oxygen areas that help facilitate the removal of nitrates and the availability of nutrients for plant roots. It’s a sort of synergistic relationship. Having a deeper substrate will allow more room for roots to grow and a rapid growing floater like duckweed can help scrub the water.

If you want more info on deep sand beds you may have to keep searching online. I don’t know how effective they truly are.

In any case, if you go with a deep sand bed or ‘mulmy’ substrate you will need to run a clean and we’ll oxygenated biological filter. This will give you a good back up. Denitrification can only occur if there is an efficient nitrogen cycle to begin with and the production of nitrate from the oxidation of ammonia is oxygen expensive. If the filter becomes anoxic then ammonia stops being converted and livestock may suffer.

I think once you achieve the balance the tank should run itself. You can apply root tabs to the substrate or drop in small amounts of fertilisers, however having lots of fish will help supply much of the nutrients. If you dose anything potassium and iron would be my recommendations. Iron in gluconate form would be favourable.

If all else fails, you have the water change [emoji846]

Keep us updated though.

 

[Luananeko]

Yes, I'll absolutely be happy to share the results! This sort of experiment intrigues me, so I think it's worth a shot! I'll stick to the 3" recommended by the article since it sounds like Bichirs tend to be diggers and I wouldn't want the bed deep enough that my bichir could do itself serious harm. Hopefully 3" should be shallow enough that worst case the sand bed won't hurt anything since it should be fairly well oxygenated all the way down to nearly the very very bottom. All the critters needed for the sand bed will help serve as live food for the bichir too

If I'm reading things correctly, it sounds like in best case this will just help my goal of keeping the tank low maintenance, and worst case (if not overdone with depth) it will just be extra noms for the bichir.

 

[Caliban07]

Sounds like you have it figured out. The main issue is ensuring the nutrient requirements of plant does not exceed input.

It’s all fine and dandy having the water scrubbed clean by plants but if you don’t add enough nutrition to the substrate the plants could suffer. That’s when you get algae.

In your case though over time the water should be pretty clean which makes it very difficult for algae to proliferate.

If you do go with duckweed you can use Darrels duckeed index coined over on UKAPS. The idea is that, because duckweed is closest to the light source, has access to 400ppm co2 from air and does not have the mechanism for large storage reserves as with most larger plants any nutrient deficiencies will show up at the duckweed first. If the duckweed is yellow or showing reduced leaf size you can add small amounts of fertiliser to the tank and wait to see a rapid response. If the duckweed has enough nutrition you can bet your bottom dollar that any submerged plants will be fine too.

Thinning out the duckweed Regularly will help and it pretty easy to do.

If you have the opposite where nutrient load exceeds demand there will come a point where plants catch up and the tank balances itself and any nutrients generated by fish will quickly be scavenged and stored. Remember to bring light intensity down if you are having nutrient related issues.

 

[Caliban07]

Thought I’d leave you with this video too.

One of my fave YouTube videos and aquarium stores!

Check out the no water change tank in 25 years Deeeeeep sand bed.

https://youtu.be/F00nqNAFisg

Enjoy [emoji846]

 

[Luananeko]

That video is so cool! Thanks!

From talking with the folks at Wet Web Media who posted the DSB article I linked earlier, it sounds like Bichir don't dig nearly as much as I thought they might, so a 3"+ sand bed shouldn't be an issue

I understand why people like duckweed, but I can't stand the stuff. It gets EVERYWHERE and I don't want it in my other tanks. I'll stick to the Amazon Frogbit or Water Lettuce.