You still need a larger tank for them.
Fish is one thing, keeping plants + fish with high light + CO2 is another.
What I'm saying is that the fish and the plants will do better, be much less work, provide more wiggle room when they have more room.
I can force just about any system. Does not mean it's easy to do nor wise.
You are right about several vs 2 due to bullying.
5 is the min, that's why 5 in 75 is nice vs 2 in a 30 etc.
I will say and I'm sure you can detect my attitude here: I have ethics issues when folks that add large fish in small tanks. It looks bad also, makes the tank look even smaller.
1.
You will likely need to do 2x a week water changes as these are adults.
40-50%. Dose after.
2.
Do yourself and the fish a favor, get CO2 gas tanks, do not do the DIY thing.
While yes, you can do it, it'll lead to issues.
You really need to do things the right way and not try and cram things into small boxes, then go cheap on CO2..............that's the most important thing in all the plant stuff and the one thing that generally causes algae and can potentially kill the fish. It pays to have the right equipment and right bioload/tank size.
Ebay sells the regs, needle valves, I use the metering valves(1/8" etc) and Victor regulators, and then a solenoid. Gas tanks at beverage places or fire equipment places, cheap and they do refills there.
Even top quality stuff might only run 25-30$ for the reg, 20$ for the valve and 45$ for a tank. You'd refill a 10lb tank once every 3 years or more.
If you added the solenoid, maybe 5-6 years.
You can also upgrade to multiple CO2 enriched tanks by merely adding one more Tee and another needle valve.
Or switching to a larger tanks later.
DIY is extremely tough on larger tanks above 40-50 gal.
Adding the light and plants is going to change things, well, you'll learn soon enough from the sounds of it.
Healthy plants = healthy fish.
EI will get the nutrients for you just fine, but the CO2, higher light and large amount of fish waste shall come home to roost.
Adding CO2 reduces the exchange of O2, but if the plants grow well, then it'll be fine. If the plants are not doing well, there's no extra O2, so you end up with high CO2/low O2 and then gasing or dead fish, and ..........the discus will die first.
All the waste generated by those fish starts out as NH4. While filters are able to handle enough for the fish's needs, the algae spores love it and are much easier to germinate when more and more fish waste is progressively added to the system. Adding that with DIY CO2, you are asking for it. If the plant has poor CO2, it'll down regulate the NH4 uptake, that will cause a little spike in the NH4 and that will lead to algae. Getting the right amount of CO2 in there using DIY steadily will be tougher than you think. Excel will not save you either.
The 2x a week water changes will help prevent some of this CO2/NH4 related issues.
I'm telling you now.
Later, you'll reflect back upon this advice.
I'd seriously consider getting a 75-90 Gallon, overflow wet/dry, UV, adding some more cardinals, see about another species of plecos, and doing a neat scape in a larger setting after you get your feet wet here.
You'll be happier, so will the fish and the viability of the tank will be much more to your liking.
On the artistic forefront:
Giant fish in tiny tanks makes any aquascape look bad.
Tiny fish in medium size tank makes the tank look giant.
I'd say 135-180 gal in the minimum size tank for Discus in scaping.
I see them in a 1600 gal tank and they act very different.
The tank looks small even there. But they have plenty of room.
Regards,
Tom Barr
