September 2026 — 29-Gallon Aquarium R&D Journal
September ended up being another important month for the 29-gallon Balance Experiment.
By this point, the aquarium was behaving very differently from the original spring baseline.
Earlier in the experiment, nitrate commonly climbed toward approximately 40 ppm within 12–13 days after a water change.
During September, nitrate stayed remarkably low for much longer periods.
The month also included:
- Two major water changes
- Continued Thrive S fertilizer dosing
- The addition of Blue Diamond shrimp from Aquashella
- Cooler seasonal aquarium temperatures
- Continued monitoring of black beard algae
- Vacation preparation
- Another opportunity to observe how the aquarium behaved under reduced feeding
As always, these observations show trends within this aquarium.
They do not prove that any single maintenance change caused the lower nitrate accumulation.
September 1 — End of the August Nitrate Cycle
Nitrate:
- Approximately 20–40 ppm
- Definitely around 20 ppm
- Beginning to lean darker, but still too light to confidently call 40 ppm
Top-off:
- 4 containers
This was Day 23 since the August 9 water change.
The important point was not whether the test was exactly 20 or somewhere between 20 and 40 ppm.
The tank had now gone more than three weeks since its previous water change without clearly reaching the approximately 40 ppm range that had appeared much faster during earlier cycles.
September 4 — Nitrate Holding
Nitrate:
- Approximately 20 ppm
- Still in the low end of the 20–40 ppm range
The reading appeared very similar to September 1.
Rather than interpreting small color differences as a real nitrate decrease, the most honest conclusion was that nitrate was essentially holding around approximately 20 ppm.
At this point, the aquarium was approximately 26 days beyond the August 9 water change.
September 5 — Preventive Water Change
A preventive water change was performed.
This was not triggered by dangerously high nitrate.
The goal was to refresh the system after the unusually long cycle rather than continuing to wait solely for nitrate to reach 40 ppm.
Water changed:
- Approximately 99% of sump water
- Approximately 50% of display water
This became the new Day 0 for the next nitrate cycle.
The completed August 9 → September 5 cycle lasted approximately 27 days.
Immediately before the reset, nitrate was still only around approximately 20 ppm.
That was dramatically slower than the original spring baseline.
September 9 — Post-Water-Change Check
Nitrate:
- Approximately 5 ppm
This initially looked surprising because the previous readings had been around 20 ppm.
The September 5 water change had simply not been entered into the log yet.
Once that maintenance event was added, the result made sense.
Approximately 5 ppm was consistent with the aquarium's normal post-water-change range.
September 11 — Top-Off
Top-off:
- 5 containers
The sump had dropped enough from evaporation to require a substantial top-off.
At this point, evaporation top-offs were still being performed using conditioned tap water.
The planned switch to distilled/RO top-off water had not yet begun because I was still waiting to establish the aquarium's GH, KH and TDS baseline first.
September 13 — Aquashella / New Shrimp
September 13 was also the official one-year anniversary of FishKeepingLifeCo as a business.
We attended Aquashella and purchased:
Blue Diamond Neocaridina shrimp
Quantity:
- More than 10
- Exact number unknown
The shrimp were added to the 29-gallon aquarium.
Because the exact number was not recorded at purchase, I am intentionally documenting the starting population simply as:
>10 Blue Diamond shrimp
This prevents creating false precision when evaluating the colony later.
Their addition also became a new livestock variable in the ongoing nitrate experiment.
September 15 — Water Test and Fertilizer
Nitrate:
- Approximately 5–10 ppm
- Low range
Temperature:
- 79.8°F
Fertilizer:
- NilocG Thrive S
- 4 pumps
- Normal Tuesday dose
Livestock:
- Normal behavior observed
- Newly added Blue Diamond shrimp had been in the aquarium for approximately two days
Days since September 5 water change:
- 10 days
Despite reaching approximately Day 10, nitrate remained very low.
This was significantly different from the original April baseline, when the aquarium was already approaching approximately 40 ppm around Day 12–13.
September 16 — Top-Off
Top-off:
- 4 containers
No unusual livestock behavior was reported.
September 22 — Water Test
Nitrate:
- Approximately 5–10 ppm
Temperature:
- 78.9°F
Fertilizer:
- Thrive S
- 4 pumps
- Normal Tuesday dose
Livestock:
- Fish behaving normally
- No obvious problems reported
Black Beard Algae:
- Still present
- No obvious significant spread
- Appeared relatively stable
Days since September 5 water change:
- 17 days
Nitrate remained in essentially the same low range recorded September 15.
This provided another data point showing that the slower nitrate accumulation seen after August was continuing into a completely new water-change cycle.
September 23 — Top-Off and Cooler Weather
Top-off:
- 5 containers
Temperature:
- 77.3°F
The aquarium was beginning to reflect the transition from summer into cooler fall weather.
During the summer, aquarium temperatures frequently reached approximately 81–83°F or higher.
By late September, the tank had returned to the upper 70s.
This reopened the possibility of eventually returning to the normal experimental aeration schedule:
Day:
- Air pump OFF
Night:
- Air pump ON with refugium lighting
However, the summer continuous-air configuration was not changed immediately.
Because vacation was approaching, maintaining the safer and more familiar configuration while nobody was home made more sense than introducing another experimental variable.
September 26 — Pre-Vacation Check
Nitrate:
- Approximately 10 ppm
Temperature:
- 76.4°F
Days since previous water change:
- 21 days
Once again, nitrate remained remarkably low.
The water change performed this day was precautionary because I was leaving for approximately two weeks.
It was not nitrate-triggered.
September 26 — Large Pre-Vacation Water Change
Water changed:
- Approximately 99% of sump
- Approximately 75% of display
This was intentionally a large reset before leaving the aquarium unattended.
Pre-water-change nitrate:
- Approximately 10 ppm
Approximately two hours after the water change:
Nitrate:
- Approximately 0 ppm
The API test appeared strongly yellow.
Because hobby nitrate testing cannot establish a laboratory-grade absolute zero, the result is best recorded as:
Approximately 0 ppm
This became the new Day 0 baseline going into vacation.
September 26 — Pre-Vacation Fertilizer
Because such a large percentage of water had just been replaced, one normal dose of fertilizer was added before leaving.
Fertilizer:
- NilocG Thrive S
- 4 pumps
I did NOT attempt to add two weeks worth of fertilizer at once.
The goal was simply to provide the plants with a normal dose after the large water change.
Vacation Feeding Plan
A neighbor was responsible for feeding the aquarium during the approximately two-week vacation.
Instructions:
- Feed only approximately once or twice per week
- Feed very small amounts
- Do not compensate for missed days with larger portions
The goal was to avoid one of the most common vacation problems:
Overfeeding by the person caring for the aquarium.
The aquarium contains established plants, algae, biofilm and natural grazing opportunities, so there was no reason to heavily feed the livestock while away.
Later confirmation:
When I returned on October 10:
- Fish appeared normal
- Nitrate was only approximately 5–10 ppm
This does not prove that reduced feeding alone produced the low nitrate level, but it does show that the conservative vacation-feeding plan did not create an obvious nitrate spike.
September Nitrate Timeline
September 1:
- 20–40 ppm
- Closer to approximately 20 ppm
September 4:
- Approximately 20 ppm
September 5:
- Major water change
- ~99% sump
- ~50% display
September 9:
- Approximately 5 ppm
September 15:
- Approximately 5–10 ppm
September 22:
- Approximately 5–10 ppm
September 26:
- Approximately 10 ppm pre-water-change
September 26:
- Approximately 0 ppm approximately two hours after large water change
September Water Changes
Two major water changes were performed during September.
September 5
- Approximately 99% sump
- Approximately 50% display
Reason:
- Preventive chemistry/nutrient refresh
- End of the unusually long August nitrate cycle
September 26
- Approximately 99% sump
- Approximately 75% display
Reason:
- Precautionary pre-vacation reset
- NOT triggered by elevated nitrate
TOTAL SIGNIFICANT WATER CHANGES: 2
September Top-Off Log
Known recorded top-offs:
September 1:
- 4 containers
September 11:
- 5 containers
September 16:
- 4 containers
September 23:
- 5 containers
Known September total:
- 18 containers
NOTE: The container is being used as a repeatable practical measurement unit. Its exact water volume has not been established, so these values should not be converted into gallons without measuring the container.
Top-off water during September:
- Conditioned tap water
The switch to distilled/RO evaporation replacement had still not begun.
September Fertilizer
Product:
NilocG Thrive S — Shrimp Specific All-in-One
Current routine:
- 4 pumps
- Once weekly
- Tuesday
Confirmed September doses logged:
September 15:
- 4 pumps
September 22:
- 4 pumps
September 26:
- 4-pump pre-vacation dose after the large water change
The September 26 dose was an additional practical pre-vacation reset dose, not an attempt to add multiple weeks worth of fertilizer at once.
Black Beard Algae
BBA remained present throughout September.
The important observation was that it did not appear to be rapidly spreading.
By September 22:
- Existing BBA was still visible
- No obvious significant expansion was observed
The strategy remained conservative:
- Maintain plant health
- Maintain stable nutrients
- Remove/treat algae on removable equipment when necessary
- Avoid aggressive whole-tank chemical treatment
- Watch the long-term trend rather than reacting to every visible patch
Seasonal Temperature Change
One of the quieter but useful September observations was the decline in aquarium temperature as summer ended.
Examples:
September 15:
- 79.8°F
September 22:
- 78.9°F
September 23:
- 77.3°F
September 26:
- 76.4°F
This was a significant change from the repeated temperatures above 80°F seen during summer.
The cooler temperatures may eventually allow the daytime air-off experiment to resume.
However, no major aeration change was made immediately before vacation.
September Livestock Update
Major addition:
September 13:
- >10 Blue Diamond Neocaridina shrimp
- Purchased at Aquashella
Fish:
- Normal behavior reported throughout the month
Shrimp/snails:
- No major problems reported
No major livestock loss was recorded during September.
The Biggest September Observation
The slow nitrate accumulation observed after the August 9 maintenance did not disappear after the September 5 water change.
It continued.
September 5:
- System reset
September 9:
- ~5 ppm
September 15:
- ~5–10 ppm
September 22:
- ~5–10 ppm
September 26:
- ~10 ppm
That means after approximately 21 days, nitrate was still only around 10 ppm.
Compare that with the original spring baseline:
April:
- Approximately 40 ppm in roughly 12–13 days
September:
- Approximately 10 ppm after 21 days
That is a major difference in observed nitrate accumulation.
But the cause remains unresolved.
Possible contributing variables include:
- Reduced feeding
- Increased plant biomass
- Refugium development
- Mechanical filtration changes
- Drain plumbing cleaning performed in August
- Fertilizer changes
- Seasonal temperature changes
- Changes in livestock
- Other biological maturation within the aquarium
Because several variables have changed, it would be scientifically inappropriate to claim one of them is responsible.
The important finding is simply:
The aquarium is behaving differently than its original baseline.
And because the original baseline was documented, that difference can now be measured.
September R&D Lessons
1. A Maintenance Schedule Does Not Have to Be Controlled by Nitrate Alone
Neither September water change was forced by high nitrate.
The September 5 change was a preventive chemistry refresh.
The September 26 change was precautionary before vacation.
Water changes remain useful even when nitrate is low.
2. Repeated Cycles Are More Valuable Than One Good Reading
One low-nitrate cycle could have been random.
By September, the aquarium had produced another long, low-nitrate cycle after a completely new water change.
That makes the trend more interesting.
It still does not establish causation.
3. Vacation Feeding Can Be Conservative
The fish did not require daily heavy feeding while I was away.
The caretaker was instructed to provide tiny amounts only once or twice each week.
When I returned, the livestock appeared normal and nitrate remained low.
For an established aquarium, avoiding vacation overfeeding may be more important than trying to duplicate the normal feeding schedule perfectly.
4. Seasonal Temperature Is Another Experimental Variable
The tank moved from summer temperatures above 80°F back toward approximately 76–79°F.
Future nitrate, plant and algae behavior should be interpreted with that seasonal change in mind.
5. New Livestock Should Be Added to the Experiment Log
The Blue Diamond shrimp addition may represent a relatively small bioload change, but it is still a biological variable.
Documenting livestock additions makes future comparisons more meaningful.
Going Into October
October begins with the aquarium returning from a two-week vacation period.
Questions moving forward:
- How quickly does nitrate rise from the September 26 ~0 ppm reset?
- Does the reduced nitrate accumulation continue once normal feeding resumes?
- How did the Blue Diamond shrimp population handle the first several weeks?
- Does BBA remain stable?
- When should daytime air-off operation resume for fall?
- What are the aquarium's GH, KH and TDS baselines?
- When should evaporation top-offs officially switch from conditioned tap water to distilled/RO?
- Does the aquarium continue supporting a roughly monthly preventive water-change rhythm?
The September data strengthens one of the biggest lessons from the entire Balance Experiment:
A useful aquarium baseline is not a single number.
It is a documented pattern.
Once you know how your aquarium normally behaves, changes that would otherwise look random begin to mean something.