WaterPig

@Creedmoor Aquatics These are really excellent points - thank you for making them. I remember starting in the hobby with like 4 plants and thinking: (1) all of these are going to live, (2) that I had a lot of plants. By the time I set up my current tanks, I had been cultivating plants for years and could properly set them up without purchasing much more. While it is possible to move plants in these tanks (I do it on rare occasions), I would recommend against it. This style of tank requires that you go into it with patience and a kind of peace with letting nature take over. Don't use dirt if you're planning on going a lot of rescaping. My water is moderately hard, so I fortunately haven't experienced any experienced the crash you're referring to.

I've been using the FF method in all of my tanks (20 gallon, 40 gallon indoor pond, 2x 10 gallon) for about two years. I used his additives at the recommended doses in all but the pond (where I skimped a bit). Each tank has only plants without any hardscape. Stuff I've been successful with: It's really easy to maintain. I just top off with well water, and never do any changes. I don't use column ferts. Stuff I haven't been successful with: Despite my best efforts, I've never been able to cultivate a true ecosystem where the fish are able to eat only what's in the tank (this is a huge focus of the FF method if you watch his videos). I need to regularly feed them or the'll starve. Stuff I find questionable: FF and other members of the community seem to believe that CO2 injection serves no purpose because the plants pull in so much CO2 from the roots. Two of my tanks use injection and the plant growth is significantly more dense and healthy. Overall, I'd really recommend going this route if you want a great looking tank with minimal work. Attached is a recent photo of my 20-gallon.

After doing a lot of searching I found this video, which may explain the problem. I really don't understand the chemistry here. If correct, the issue was doing a substantial water change from cold well water without properly aerating it first. I've started removing water from the pond, aggressively mixing it (pouring it from one bucket to another from several feet above), and then returning it to the pond. After many many cycles of this, the fish appear to be more active now... but that may be wishful thinking.

The setup: I have two goldfish in a pond liner. In order to move it outside for the summer, I drained and refilled most of the water. It's a bare-bottom liner with accumulated mulm, leaves, and one piece of wood. They've been living in there for about 3 years. There are some surface plants and a few below (moss + java fern). The sides are also covered with algae. Water quality tests seem good: 0/0/0. The pond has good aeration, though the O2 level this morning was ~6 mg/l in a salifert test (unsure if I trust those). I'm using well water to fill the pond - I use the same water in my other tanks with smaller fish, no issues there. The problem: Both fish appear to have gas bubble disease (GBD). They have formed bubbles in their fins and behind their eyes. It looks consistent with photos I see online. I suspect at this point neither will make it. The question: How did I mess this up, and is there anything I can do?

For my 20 high, I'm using a CO2 reactor kit from Amazon. It came with a diffuser, solenoid, pressure gauge, etc. Every 2-3 weeks I clean out the reactor, mix up some baking soda + citric acid powder + water, and away I go. After a lot of experimentation with diffusers, I found the simplest solution was just to insert the CO2 output line into my powerhead air intake (in my case an AquaClear 20). Surprisingly, the powerhead was able to chop up the gas into fine enough bubbles that will float around my tank. For a demonstration, see the YT video "Best Co2 Diffusers Reviewed + Explained". I'm aiming the powerhead across the back wall of my tank. Combined with the circular downward force from my HOB, it seems to spread the bubbles around the tank reasonably well. I found that a lot of getting DIY CO2 to work for you is in getting the bubbles to distribute properly so they actually land on your plant leaves. If you have uneven flow, some plants will get all the CO2 and/or some will simply rise to the surface and escape. As for not gassing your fish, make sure to get a drop checker so your don't run too much CO2 during the day. Get everything you have on a timer. I'm using the "Kasa Smart HS300 Plug Power Strip" which lets me individually program timers for everything in my tank (air pump, CO2 solenoid, filter, heater, lights, powerhead). That power strip is probably the best purchase I've ever made in terms of tank equipment. I've got the lights on for 8 hours a day + 1 hour on each side for ramp up and ramp down (fluval 3.0). At the start of the ramp-up, the air stone goes off (Aquarium Co-op pump + air stone), the powerhead comes on and the CO2 comes on. At the start of the ramp-down, the process reverses (with an hour gap in between the CO2 turning off and the air starting). In theory, all of this should help the plants get O2 and night and CO2 during the day. Through the magic of the powerstrip (and the fluval light app), I don't have to touch anything to make all this work.