Hi, I recently bought a Pinpoint pH Monitor that has been calibrated and I compared the results with the API liquid test kit, to be sure. I have African cichlids and I would like to keep my water's pH, or I should say hardness higher, but most importantly, stable.
is about 5.5 - 6 dKH
is 8 dKH
I've noticed that my pH moves up and down depending on the time of the day. This is what I've noticed:
Little after Midnight (around 2 AM), early morning (until 11 AM or so) 7.61
Late morning, afternoon 7.75
Late afternoon, night 7.81
Is this normal?
FYI, I have glass lids which stay closed all the time, I run an airstone in the sump, Kroalia air pump 1400, the tank is 120 gallons and it currently holds 9 Malawi cichlids all of them being under 5".
The tank has been set up for around 4 months and with fish for about 2 months. Fishless cycled 3 months ago.
I perform weekly water changes of about 20%. My nitrates stay under 20 PPM
Also, my old light fixture broke, so I run the tank for about two months with no light, just natural light from the living room windows but no direct sunlight, and I had noticed a few spots of brown algae in the sand in the past, but I'm talking about less than half an inch of brown algae in the whole tank; However, now that I got a new light about a month ago, brown algae has been growing a lot, everywhere, during the last two weeks. This is my light schedule:
3 PM - 9:45 PM - Daylights 2x 10,000K T5 HO
9:15 PM - Midnight - Actnics 2x T5 HO
24/7 (except for when Actnics are on) 4 blue lunar LEDs
The fixture is a 48" Coralife Aqualight T5 HO
I know lighting has nothing to do with pH or hardness, but I'm still giving you these information just in case. It doesn't hurt.
and the lids being closed has something to do with the swings in pH?