Algae Bloom / Green water

I will check pH morning and evening for a few days.
With CO2 running, the pH tends to drop a bit later in the day, as the CO2 solenoid is connected to the lights, and starts when the lights are switched on in the morning.
This evening the pH measured at 7.3.
I have not tested kh or gh.

 

That doesn't seem high at all, sounds like the rock isn't having any significant effect on your pH at this stage. Your tap water is probably around the same pH in Centurion. I'd still suggest checking the pH over time to see if things change over the next few months. If you want to confirm that its dolomite, try a little drop of dilute HCl (pool acid) on a spare piece of the rock, if it starts fizzing it's a carbonate. Although I'm pretty certain it is (dolomite is one of the ways I earn a living as an engineering geologist)

 

Our tap water generally has a pH of about 8.4, which is much higher than it used to be in the past.
Judging by the scale build-up around the edges of my tanks, the water is harder than concrete.

pH was measured at 7.6 this morning, one hour after the CO2 was switched on.

 

Sheesh, that is high out of the tap. Sounds like your pH isn't fluctuating too much with the CO2. I wonder if that has something to do with the dolomite acting as a pH buffer? Either way, your tank is looking great, I wouldn't change a thing. And you've sparked my interest in UV sterilizers

 

I'm in Waterkloof heights, pH of my tap water is around 8.5, a year or so ago it was around 7 to 7.5, maybe as a result of the drought we're getting water pumped from different sources hence the increase in hardness?

 

pH in the tank seems to be quite stable.
25/09/2015 Morning 7.6
Evening 7.3
26/09/2016 Morning 7.4
Evening 7.3
27/09/2016 Morning 7.4

It seems pH is highest directly after a water change, an stabilises at around 7.5, with fluctuations of a point or two depending on the CO2.

 

That's some good info there Pezulu. If you start up your CO2 an hour or two ahead of your lights, would be interesting to see if that range varies a bit more.

 

That sound right, a decrease in pH should be gradual and will be impacted by waterchanges, both the volume and pH of your tap water

 

If I can remember correctly my co2 always came on an hour before lights on. So by the time lights go on theres already a good amount of co2 in the water for the plants.

The Tranquility Effect

 

The CO2 in my tank is connected to the light switch, so it comes on at the same time as the lights.
It hasn't bothered me yet, and the fish and plants seem happy with the way it is.

 

I can guarantee you that your plants will grow better if you put your solenoid on its own timer. Your plants will start pearling sooner

The Tranquility Effect

 

After a 30% water change yesterday, the pH was 8.0.
This morning the pH was measured at 7.6.
Will check again to see what it is this evening.

It seems the dolomite is not having much of an effect on the pH of the water, and the CO2 is definitely helping with the pH.
A pH of 7.0 would be ideal.

 

I can guarantee you if you let your co2 come on an hour before your lights that your plants will start pearling faster your ph will also drop a bit more. You can go read on apsa everyone on there also starts their co2 an hour before lights on. Just my 2 cents worth and just trying to help out a fellow hobbyist.

The Tranquility Effect

 

At this stage the costs outweigh the benefits.
The plants are growing well enough, and the fish and I are happy.

 

Then all is well yes sure you will use more co2 can remember my co2 lasted a couple of weeks. Also remembered just now that co2 went of an hour before lights of so if you do it like this you wont really use more co2

The Tranquility Effect