Algae issue

[Wildwhimsy]

Looking for some advice on an algae issue that seems to be escalating pretty quickly. The algae I scraped off the glass was noticeably back within 24 hours, and I’m now seeing more of it on newer plant growth as well, not just older leaves. I recently installed lily pipes and an inline diffuser, so flow and CO2 distribution should theoretically be improved, but I’m wondering if I’m missing something balance-wise.

Tank is a UNS 60U with an exact water volume of 16.6 gallons.

Current lighting schedule:
• Sunrise starts at 7:30 AM and ramps for 45 minutes
• 100% intensity from 8:15 AM–4:15 PM
• Sunset from 4:15 PM–5:00 PM
• Total photoperiod: 9.5 hours
• 8 hours at full intensity

CO2:
• On at 5:30 AM
• Off at 4:00 PM
• Drop checker is nearly yellow
• Hanna CO2 test previously read around 25 ppm, though I’m not fully confident I tested at the ideal time


Thursday I did a 10 gallon water change, which should be about a 60% water change on this system.

Parameters before water change (5/21):
• pH: 7.0
• NH3/NH4: 0
• NO2: 0
• NO3: ~20 ppm
• TDS : 250

Parameters after water change / next day (5/22):
• pH: 6.8
• NH3/NH4: 0
• NO2: 0
• NO3: ~20 ppm
• TDS: 215
• GH: 7 drops
• KH: 3 drops

Before testing on 5/22, I added about 1 gallon of RO/DI water to replace evaporation, along with 1 pump of APT 3 and a small amount of shrimp mineral.

I’m trying to figure out whether this seems more likely related to:
• too much light
• unstable CO2
• excess organics
• nutrient imbalance
• tank adjustment period after changing flow/diffusion
• or something else entirely

Would especially appreciate input from anyone who has dealt with algae increasing rapidly. This is my first high tech setup and I never dealt with algae in my other planted tanks.

 

[Unexpected]

Drop your light schedule to an eight hour cycle. Not that more hours can't be done but more isn't necessary either. I would also temporarily lower the intensity. Shoot for 50 to 60 PAR at the sub. What is your substrate? 25ppm CO2 is low, maybe check it again when CO2 has been on longer? With the Hanna checker, my tanks are above 40 and one tank is 52.

 

[Wildwhimsy]

thanks for the response! My substrate is fluval stratum, a mix of year old and brand new. When I checked with Hanna it had been on for a while. I as thinking of checking with it right at lights on, maybe midway through photo period and then lights off. I’ll reduce photo period by an hour and intensity down to 75 percent and see if that helps at all.

 

[Unexpected]

Startum isn't the most nutrient dense, I'm seeing just a bit of deterioration on the lowers of that Ludwigia. I wouldn't do it yet while make the light changes, but keep in mind you may need to bump up on dosing. See what happens with light first.