It's looking like the tank is continuing to improve and grow well week to week. Plant growth rates are speeding up and the width of certain stems has increased tremendously. This is most apparent on the Ludwigia sp. 'Meta' and Rotala sp. 'Singapore'. I pulled up a few stems and I can see decent rooting on the majority of the plants and I can also see side shoots and aerial roots forming on the new growth. All good signs that I wasn't seeing before the switch to RO. The pearling in the tank is also significantly better than at the start of this month implying that the plants are growing much faster. If I knew how to post a video, I would show off the pearling in the tank because it's getting pretty fun to watch. I did have a few stems melt back in some groups (Rotala macrandra 'green' and Ludwigia arcuata) and this is something I'll need to keep an eye on. If the tank continues growing at this rate it should be be full of healthy plant mass soon.
Despite the solid plant growth and the constant trimming of old growth, the green thread algae continues growing quite aggressively. I spend far too much time pulling it out each week and cleaning up the plants is making water changes extremely time consuming. I was reading the tank journal by Unexpected, who seemed to have similar issues for a long period of time, and he commented that lowering light was the key to getting over the algae. I tried lowering my lights to the lowest setting and it didn't seem to help that much, so I've thought my light level was reasonable. I revisited this by searching for PAR data for Prizms and realized my lights, even on the lowest setting, are extremely bright. Below are the measurements for a single Prizm on the lowest settings over a 13" by 13" square at 18", 24", and 30" height. I have three 16" Prizms over my 48" tank hanging 21" over the substrate. When you account for the spread from the adjacent lights, I've been running extremely high PAR and this is probably why its been so hard to get over this algae phase. I raised the lights from 21" to 28" over substrate hoping that would get me right around 100 PAR, which is a reasonable level for everything that's growing in my tanks. I'll definitely lose a little bit on color, but that's worth it if it helps the plants outcompete the algae.
I made three other significant changes to the tank this week even though I said I'd keep it consistent.
1) I changed out the in tank heater for an inline Chihiros Heater Pro. This cleaned up the look of the tank quite a lot, but it also seems to heat much more efficiently. I'm really happy with the quality of the heater and find that its very convenient being able to change the power as needed. When I water changed yesterday the water temp dropped to 65F and I was able to get it back to 72F in ~1 hour by temporarily changing the heater power from 400W to 800W. The plants underneath the in tank heater also grew angled and I'm hoping they can grow upright now that they have unrestricted light access.
2) The Ludwigia arcuata and Rotala macrandra green that melted a little bit are both in the same region of the tank and it's possible that with more dense plant groups the CO2 distribution has become suboptimal. I changed out the stainless steel filter outlet in the right hand side of the tank with a spray bar to make sure the entire tank gets solid flow with CO2 rich water. I had to design a couple 3D printed connectors to setup the spray bar, but it was all done pretty quickly and has been functional for a few days. I printed the parts in grey, which doesn't match well with the black used for the majority of the connectors, and I will need to reprint in black at some point to clean up the look.
3) I sometimes get very busy and forget to dose my tanks, so I got the Chihiros dosing pump to help with consistency. Chihiros did a very good job with this and it's significantly better than the Jebao dosing pump I used back in 2018. Because I got the dosing pump, I decided to settle into a "final" dosing strategy. For macros, I'm going to dose 28NO3-8PO4-36K weekly with half of this front loaded on water change day. The remaining amount will be distributed throughout the week in 2PPM
NO3 doses. I settled on this dosing scheme because it provides reasonable stability over a range of daily uptake values (based on Rocco's awesome nutrient accumulation calculator) and it'll allow the plant uptake rate to dictate growth rate. When the tank is really grown in and using a lot of nutrients, the steady state values will be lower and growth will be limited. When the tank is freshly trimmed and needs some help growing in, the steady state values are higher and will allow for faster growth. I've almost always done EI dosing in high tech tanks with 3 doses per week, so I'm not concerned about the total weekly dosing levels. It'll be interesting to see if this strategy helps with consistency and reduces stunting in sensitive species though.
For micros, I'm settling on 0.42
PPM Fe weekly (with the corresponding amounts of micros based on the recipe from Burr740 shown below) dosed at 0.06 PPM Fe daily. I picked to dose 0.42 PPM weekly because that's cleanly divisible by 7 and made the math look better (notice I did the same for NO3). I mentioned last week that I wasn't planning to change micros this quickly, but the plant growth has been better since running 0.3 PPM Fe+micros weekly and I've never had bad luck with 0.45 PPM Fe+micros dosed weekly. Since I'm doing daily dosing I'll pay close attention to how the plants look at the end of the week to see if I need to dose down. I have enough micro and macro solution made for 1-2 months and will stick with this until they run out unless something goes wildly wrong.
