i just set up a new planted tank(40g) with about 3 inches of Eco-complete as a substrate, my Tap water's kH is 40 ppm and the kH in my tank 36 hours after set up is 75 ppm .

Right after set up i adjusted my pH contoller to 6.3 according to my tap water's kH this should give me about 33 ppm of Co2 i did not test the tank's KH the plants where pearling .

The next day (this morning) i tested the kH and it was 75 ppm so i raised the set point on my pH controller to 6.6 to maintain CO2 near 30 ppm and i had very little pearling

So my question is :Should i adjust my Co2 levels according to my tap or tank water?

I did not add any buffers or chemicals to my tank other than tap water conditionner and some substrate fertilizer (www.aquariumplants.com) home brand

I have not started fertilizing yet. I will tommorow (third day after set up)

I have heavy plant load and no fish yet so i can't see if they are gasping

i ordered a powerhead to add some surface movement i have close to none(i read all the posts here)

At first i tought there could be some limestone build up in my hot water tank i had only tested the cold water before (I had limestone build up at my previous home raising both kH and gH) but that was not the case here exact same kH of 40 ppm

So i put the set point on the pH controller back to 6.3 and the pearling started right away??? (i guess that answers my question but what about the the kH ?) and the O2 bubbles are trapped under the surface scum

Could all the pearling issue be simply the lack of surface movement , gaz exchange?

gH 100mg/l
kH 75 mg/l
NO2 ~ 0.3 mg/l
NO3 ~ 7 mg/l

Any and all tips and suggestions will be gladly accepted as it is my first High light (4.5 watts/Gallon) co2 injected PMDD planted tank


Yves

You need to start fertilizing right away. The plants need the fertilizers to grow from the beginning. And, you should use the KH you get by testing the water to determine what pH you want for the CO2 you want. But, be aware that this will most likely overestimate the CO2 in the water. Since you have no fish, why not jack up the CO2 much higher and keep it there during the time the lights are on, until you do add fish. Once you add the fish you have to be careful not to have too much, but the plants will have no problem with high CO2.