[Bill_L]

My five year old 75 gallon chichlid planted tank has a mix of pea gravel and some brand (can't remember) of fairly course black inert sand. My plants thrived for a few years and after long periods of neglect started to die off. I still had a few plants hanging on, and recently restocked with amazon swords, java fern, and anubis. The java and swords are struggling. I recently did a major water change, restocked my canister filter with fresh media, removed all of the algae covered rocks, and a substantial piece of Juniper root (looked cool, but not sure what it did to my water) and added a nice piece of cholla wood. I've also got a corner sponge filter on the way to be used along with the canister. Plan to pressure wash and/or bleach the big rocks. I've also found someone to rehome a couple of really big plecos and other fish that are crowding the tank. I plan to keep a pair of the Kribinsis and rasbora and tetras. The water parameters are all good now and I'm wondering if I should go ahead and change out the substrate, but not sure how to accomplish this with the fish and plants, without removing them. Any pointers appreciated, thanks in advance!

 

[zdrc]

All (I think) aquatic plants can get their nutrients from the water column. You don't need special substrate to grow plants. It can help but it's not necessary if you dose a liquid fertilizer. Your current substrate would probably work fine.

Thinking more broadly, this is perhaps the most substantial difference between terrestrial plants and aquatic plants. Substrate is super important for terrestrial plants because they don't have any other way to get fertilizers. Therefore, a lot of people assume substrate is really important for aquatic plants, but they forget that aquatic plants are continuously immersed in fresh fertilizer. On the other hand, aquatic plants are essentially suffocating all the time because they're underwater (not enough dissolved CO2). Terrestrial plants have much better access to CO2.

If I were you, I would take the money that I would spend on substrate and instead buy a CO2 injection set up and some liquid fertilizers (the NilocG brand is good). Of course, if you don't like the look of your current substrate, by all means replace it.

If replacing the substrate, I would take out all fish, plants, and decor and then remove as much water as possible. I'd scoop out the substrate and then replace with the new, rinsed substrate. Then put everything back in. It's a pain. Maybe someone will chime in with a trick to make things easier.

 

[Bill_L]

Thank you for the tips! I do like the substrate and will probably keep it. I'm already dosing the water and the parameters all look good after a week with the new filter media and removal of as much junk and large algae covered rocks as possible. I've backed off on the light a little, to see if that helps the yellowing swords, which are growing new shoots like crazy, but the stalks and leaves are struggling. As far as C02 injection goes, I set up a really nice system a few years back, but during the pandemic, I let the tank really go and the CO2 was not helping. And, a local gas shop burned me on a refill that was not totally full. The closest location to get it refilled reliably is a 40 minute drive. I wound up selling the whole system and I'm trying to go back to low tech approach with a renewed commitment to take better care of the tank with regular water/filter changes and monitoring, less fish, etc. I had no problem growing swords, anubis, water wisteria, hornwort, and java fern before CO2 dosing the water pretty regularly, and keeping the tank clean. I've thought about maybing trying the low tech method of co2 but that just adds more work and maintenance. Maybe I'll reinvest in a system. I've checked out some of the paintball canister options, and they may be easier to get refilled, don't know.

 

[Bill_L]

I decided to go back to c02 and just ordered a 5lb tank and need to get the regulator and other accessories. Hoping to get it right this time with some lessons learned and hopefully some tips on how to succeed. The first lesson is c02 doesn't really help if you let the tank go and never clean it! The other questions relate to how to apply the c02, direct injection or in tank injection. On my previous setup I had the high quality c02arts dual gauge regulator and an inline diffuser on the output of my fluval 407, which uses physical, bio, and chemical (charcoal) filtration. The c02 tank was set up underneath with the inline diffuser several inches from the output of the filter. Refilling the bubble counter was a pain because the line had to be removed, and would sometimes leak. This time I'm thinking of using a good intank diffuser placed near the bottom in the center of the tank. Several factors pose questions to a noob like me for either the inline or the in tank method. The filter output just below the water line is about five inches apart from the filter input about six inches off of the bottom of the tank. Does this affect c02 distribution? I'm also running a corner sponge filter on the other end of the tank and a 1350 GPH circulation pump on this end a few inches from the water line facing the main filter end of the tank. Do the sponge filter and the circulating pump have any effect on the c02 injection? Thanks in advance for any information. I'm thinking about buying this regulator that gets really great reviews. GLA GRO Aquarium CO2 Regulator

For reference, some recent pictures for reference. The tank looks way better after the thorough cleaning and rehoming some of the big fish that were causing such a mess. I've been dosing with 2hr Aquarist 1 2Hr Aquarist APT Zero and flourish excel.