hi again!

Your advice following, I lowered my pH by 0.1 and increased my PO4 addition to 0.3 mg/l/day. I already see results that I want to discuss.

First of all my settings (it may help)

Tank: 100x40x40
Pomp: eheim professional (containing just white foam)
CO2: pressurized, administration by wooden airstone
Substrate: amtra plant depot (1.5 years old)
Light (30 watt per TL):
1x Philips TL 840 (middle): 13.00-23.00
1x Philips TL 830 (middle): 13.30-22.30
1x Philips TL 830: 19.00-22.00
1x Philips TL 840: 19.00-22.00
1x Philips TL 840: 19.00-22.00
liquid fertilzer: 3-4x/week 8 ml flourish, 3-4x/week 8 ml flourish iron
pH: 6.3 (now 6.3 again)
KH: 4.0
GH: 6
PO4: 0.3 mg/l/day (the actual PO4 level in the tank is quite low, 0.5-1 mg/l)
NO3: 2 mg/l/day (NO3 levels are rising during the week, 17 mg/l directly after waterchange, to 25 mg/l after 7 days)
Conductivity: 480 µS
Water change: 60 litres per week, 30 litres of RO water and 30 litres of tap water (pH 8, KH 7-8, GH 8, 660 µS, NO3 10, PO4 0)


I saw that my shrimps were near the surface or even above. Really abnormal behaviour! I also saw one dead shrimp. My guess is that the decrease in pH from 6.4 to 6.3 was too much. too much CO2. I didn´t degass my aquariumwater for 24 hours yet, but the pH of the sample that I took from the aquarium this morning is now (6 hours later) at a pH of 7.6. So it is more than one point, suggesting that I have enough CO2 in the tank even at a pH of 6.4 do you agree?

The other thing that I saw (and really liked!) can best be explained by a drawing.



So I see that the CO2 bubbles are pushed by the current of the filter outlet towards the front glass. By eye, I can see the bubbles reach the glass. the complete left side of the front glass is in direct contact with the bubbles. The right side is not. Now I see is that the left side is free of algae while the right side gets single stranded fuzz algae. (additional info; the outlet of the powerhead is not directed towards the glass, so I think there is less current near the front glass at the right site of the tank).
Now I wonder: WHY? Is it the higher CO2 concentration on the left side of the tank (not measurable by my pH meter), is it the stronger current or is it a combination of both?
To test this, I replaced the powerhead in such a way the current from the powerhead reaches the glass at the same angle as the current from the filter outlet. we will see!!

For the nitrate and phosphate: 0.2 mg/l/day nitrate is for the moment enough. during the week the level is still rising. 0.3 mg/day phosphate does not provide enough PO4 for a stable level: the PO4 levels are still dropping during the week. Should I increase the PO4 addition even more? (values are measured by photospectrometer)

One other thing that I wanted to ask is that the new leaves of the proserpinaca palustris are a bit small and especially in the morning they are curled. The curling is less in the evening? What is causing this?

greets,

yme