Starting my first 125g with some questions!

Hi all, I’ve just recently built an 8ft long stand to house a 75 gallon I recently picked up, so naturally with all that extra room, I upgraded to a 125g for the first time!

Because this is my first build at this size I really want to do this right and make this my main aquarium. I’m planning on scaping and planting it heavily. I’ll be running a new eheim 2217 which is rated to filter 160 gallons.
This will also be my first time testing the waters of CO2.

Although I have lots of experience in planting and scaling aquariums I am a bit confused by CO2.
My two main questions while getting into this are:
1.How complicated does a co2 setup on this size tank need to be and how inexpensive can it be without robbing the tank of anything?
2.I wanted to see if anyone had any opinions on stocking and bioload. I am hoping to have around
-Around 4-6 angelfish
-6-8 Geophagus
-3 Electric blue acaras
-1-2 groups of large body tetras
Bleeding heart tetras
Emperor tetras
Colombian tetras
-Group of corydoras
-BN plecos or whiptail catfish

Any opinion is appreciated, especially with stocking choices as to me this sounds like a lot of fish but I’ve never had a tank this large and I see people with setups like this frequently. Thanks for any feedback!

I really like my CO2Art system. I bought their larger in tank diffuser for my 75, but if I went to a larger tank, I'd go for their in line diffuser, but that is a personal preference. Get a 10# tank at minimum. I'm running a 5, but I have a half dozen of them because I also brew beer so they are multi purpose. I quality of the CO2Art is great and have been really happy with it. You can try a DYI system that uses fermentation to create CO2, but they aren't as precise.

Can't speak to your load. I currently have a total of 40 fish/shrimp in my 75g. Mix of Rummy Nose Tetra's, a Pleco, Yoyo Loaches, Amano Shrimp, couple Neon Tetras and a Tetra type fish that I can never remember the name of and 4 Angels.

What are the tank dimensions (length x width x height)?

What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website (Water Analysis Report) or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

Depending on what the GH of your water is, will determine what fish you should keep.

Angelfish, discus, most tetras, most barbs, Bettas, gouramis, rasbora, Corydoras and small species of suckermouth catfish all occur in soft water (GH below 150ppm) and a pH below 7.0.

Livebearers (guppies, platies, swordtails, mollies), rainbowfish and goldfish occur in medium hard water with a GH around 200-250ppm and a pH above 7.0.

If you have very hard water (GH above 300ppm) then look at African Rift Lake cichlids, or use distilled or reverse osmosis water to reduce the GH and keep fishes from softer water.

--------------------

Columbian tetras are fin nippers and might give the angelfish a hard time.

What species of Geophagus? Some are peaceful and some aren't.

Maybe too many bottom dwelling cichlids, depending on tank dimensions.

If you keep tetras in a big tank, go for 20-30 of each species so they group up and don't disappear among the plants.

--------------------

In big tanks it's a good idea to have a decent quality carbon dioxide (CO2) unit if you plan on having one. Using home made CO2 on a big tank can be difficult to control and get the correct amounts. If you want supplemental CO2 in the tank, find a good brand and set it up so it's automated.

If you do add CO2, make sure the KH is 100-150ppm so the pH doesn't drop from the acidic gas (CO2 is acidic).

Having said that, you could try running the tank for 6 months without CO2 and see how it goes. Then if you want to add CO2, you can add it later. Most aquarium plants don't need supplemental CO2 and there's plenty in the water from the fish, filter bacteria, and it gets into the water from the air.

The following link has some basic information about aquarium plants and might interest you.

The tank I have now in a 72x18x21. I know my city water ranges in the middle for hardness with:
Ph of 7.2-7.4
Gh of 150-180
Kh of 80

I have had lots of success keeping South American fish previously and have had lots of success in lowering my ph naturally using woods and organic matters to get it down as low and a 6.5ph! The way I plan on setting this up is to have it running for around 4-6 weeks without fish in it, only with the scape and plants to dial in all my water parameters to acceptable levels.
This includes co2 as I’m not looking to add it in until I understand how the tank will run without it, which to grow plants I haven’t had success with in the plants I assume I will have to eventually to take it to the next level. I have a dedicated planted aquarium store near me that I will visit and explore options on setups with them as well

That is good to know about the Colombian tetras as I’ve never kept them before.
As for geophagus I am open to suggestions, I’ve seen the basic brasiliensis geophagus which look amazing but these fish will be a first if I go along this route and any other suggestions would be great.

Geophagus brasiliensis and most other big Geophagus dig and will make a mess of your plants. The G. brasiliensis should be kept in pairs and grow to 6-8 inches long. Smaller species that grow to 4 inches will do less earthworks and are less likely to dig up all the plants, however they still might move a few.

I have had plenty of plant tanks and only one had supplemental CO2. It did slightly better than the others but the amount of stuffing about and money setting up the CO2 wasn't worth it as far as I am concerned. If the local plant shop says you have to have supplemental CO2 to grow plants, they are trying to sell you stuff. By all means have a look there but don't be forced into buying something you don't necessarily need.

Your KH is fine for stabilising the pH if you add CO2. A fraction higher would be better but 80ppm is fine.

Thanks for the advice on the geophagus! I have no shortage of LFS around me and I will look to see what the local supply of geophagus is like and what species we have. Maybe someone could recommend some names of smaller species that would play well with their potential tank mates.

I’ve resisted the recommendations on co2 previously on my smaller setups since I was quoted something like $400CAD including a co2 tank and on my 30 gallon it just wasn’t near enough worth it lol. If everything goes well in the setup then I might still hold off but still playing with the idea of it

My pressurized CO2 system ran on a 50 gal. But at the time I purchased the system I was very budget conscious. So, I needed to get a CO2 system for as little cost as possible. Here is how I did it.

1. I purchased a 6 gal. aluminum bottle and my dual stage regulator from a beer supply company.
2. I purchased co2 resistant tubing, a bubble counter and a Clippard needle valve elsewhere.

I did not use a solenoid or timer and I ran the co2 24/7. I figured at worst I would out-gas CO2 using an air pump on a timer to run overnight
if I need to do so.

I had no room in the tank or outside of it for much more than that. So, to diffuse the CO2 I elected to run it directly into the intake of the canister filter that would go on the tank. So, I chose an Eheim Pro II filter. I figured any other brand was likely th have issues with gas bubbles going through it. So not other brand seemed safe.

The system ran great. it took me a little time fo figure out if I ran a somewhat lean mix of CO2 I could run it 24/7 and did not need to out-gas CO2 at night. That Eheim canister was my first canister.

I set up this tank and CO2 system in late 2002.early 03. I ran it for almost 10 years continuously. But the amount of work required to keep the plants in check made it the tank that required the most weekly maint. becuase of the amount of pruning etc, the plants required. So after 10 years I gave it up. I sold the CO2 system and then upgraded the tank to a 75 gal. I kept the canister however. It had run great the whole time I ran the CP2 through it.

I started in fish later in life and I am now 76. I have been breaking down tanks and selling fish for a while. In the spring of this year I broke
down that 75 and after 20+ years of continuous use with 10 being with CO2 pushed though it., The filter still runs great and as quietly as the first day I used it. I cleaned it up and plan to sell with all new Eheim media included in the near future.

So, I did almost nothing special in terms of the CO2 from a diffuser to all the other fancy gadgets that get sold for plant folks. I own none of them. My substrate was plain coated small size tank gravel. My substrate fertilizer has alsway been Jobe's Spikes for Lush Ferns and Palms and my liquid ferts have been Tropica's and still are.


At my peak i had 13 planted tanks but only the one with CO2. The non CO2 added tanks all got/get Flourish Excel. I still have 7 planted tanks today. One, with a group of corys I have been trying to spawn so it does not get the Excel but the other 6 do. I still use the Tropica liquid ferts and the Jobe's spikes where needed.

There are a ton of very pricey things one can buy for planted tanks, I tend to avoid them all. Here are pictures of that 50 gal.CO2 added tank as it was redone over the years (it is terraced and has 3 different levels).





As always, this is just how I did things. It is not necessarily the only nor even the best way. But, it was definitely not the most expensive way.

edited for typos and spelling

Thanks for the insight! The tank looks great!

I still have lots to research in terms of CO2 and if I will even deem it necessary once I’ve gotten the tank up and going, seeing as the geos are diggers I might opt for hardier larger plants, such as swords and vallisneria for the floor, maybe scattering some smaller crypts and dwarf sag around and try to protect the roots with rock to keep them from getting stirred up.

A couple plants I’ve never been able to grow in my aquariums surprisingly are pogo helferi and hydro pinnatifida which I can’t figure out why but maybe I’ll crack the code lol.

If I opt for geophagus which I am leaning towards I will have to be mindful anyways. I checked in with my LFS and they have sveni which I was most interested by along with a couple other species.

Update on the 125:
When I last posted here I hadn’t even finished the stand for the tank but it is now not only cycled with fish but thriving! I was able to pick up some cycled media from a great LFS and some stability to kickstart the process. Although still a work of progress I have a great start with plants and fish with the current inhabitants being:
6 Angelfish
-3 Koi
-3 Bulgarian Sealpoint
12 Bleeding Heart Tetras
12 Black Emperor Tetras
2 Banjo Catfish
1 Twig Catfish
1 Colombian Zebra Pleco

So far I’m thrilled and can’t wait to finish my stocking, just waiting for all the fish to settle with bioload in mind.
With that being said I came across a great deal for Panda and Sterbai Cory’s and was wondering how many would comfortably fit in a tank this size as I’ve never attempted it. The seller has 20 Pandas and 25 Sterbais at half the price they are in store so I’m eager to hop on them soon. Any advice would be appreciated!

The tank is 72’ x 18’ x 22’ by the way with an Eheim 2217 filter.

Morasea said:

The tank is 72’ x 18’ x 22’ by the way with an Eheim 2217 filter.

Click to expand...

If you increase bioload at all I really think you are going to need more filtration. I am not an expert on large well planted tanks (which I know will help with some waste removal), but I run a 135g with a load of tetras and sterbai corys. For the large fish I have one large blue acara, one large angelfish, one large golden gourami and a lovely peaceful strawberry leporinus. I need 3 x Eheim 2217s to keep up all of them. Remember Angelfish get bulky in adulthood, as do most cichlids. Its best not to just plan for a tankfull of juveniles.
As for stocking I think its looking good, and almost done. Corys - definately sterbai if the tank is at typical tropical temps. Pandas are an almost temperate species really.
As for cichlids, I wouldn't add too many or you are going to start having aggression (and bioload) problems. Maybe an electric blue acara and a small number of bolivian rams ? Acaras do not need conspecifics for a happy and satisfied life, and can be quarrelsome with each other so a lone one does work very well. Bolivian Rams are nice and peaceful, would also like your water and would complement all the rest nicely IMO.

I’ve definitely deviated in stocking choices from when I started out but as for filtration I’m planning on adding one more filter in some capacity, although I’m not sure exactly what kind I’ll add on. I’m very satisfied with how the tank is running currently and don’t mind a slow burn when it comes to finishing it because it keeps giving me things to do that I enjoy.

The person I was supposed to be buying the Cory’s from ended up falling through so I lost out on half price Cory’s but that’s alright, I’ve been loving my banjo catfish anyway!

I still plan on mixing the different cichlids as I do believe the tank is a substantial enough size to try doing it successfully, although I am treading lightly and keeping a very close eye. I bought 12 black emperor tetras at a show, which I love, but know I will inevitably have to move them as my 3 EBAS grow in size. I have yet to add any geophagus as the stores by me don’t have full stock of sveni, which they believe to be the tamest out of all the species they sell and I am also using their best judgment along with mine.
Needless to say I’m loving the tank and haven’t enjoyed fish keeping this much in ages!

Wanted to post a little update on the tank and show it’s thriving! My electric blue acaras have spawned twice now and look fantastic! They’ve stayed super peaceful other than when defending their young. I also have a group of 6 red head tapajos in here that I’m hoping will spawn soon. I’m thrilled everyone is getting along great and growing great! Loving the plants and all the different species of fish, really showed me what a community aquarium can be.