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Fine tune, pH profiling

Florin

Seedling
Joined
10 May 2018
Messages
5
Location
Cluj Napoca
Hello to all,

Even if this is my first post here, I read the forum for some time and I've learned a lot of things. Thank you for that!

I am in the phase to fine tune the CO2 system. I just received a pH pen (unfortunately a cheap one), so during the weekend I'll be able to do a pH profile and I'll try to adjust CO2 injection as it should be (at least I hope that :) )

First, aquarium details:
-tank: Eheim Vivaline led 180L (WxDxH = 100x40x45 cm), 135L water
-filtration: Eheim Professional 4+ 350, 1050 lph, fully filled with Matrix and SubstratePro; 80 cm spray bar on the back wall, 8cm below water level; Eheim microSkim on the back wall; flow is fine, plants are gently swaying
-substrate: Dennerle Scaper's Soil 24L, 5cm front, 7cm back
-light: 2 x Eheim classicLED 17W, 2 x 1300 lumen = 2600 lumen in total (can't find any info about PAR); lighting period is 7 hours
-CO2 - 2 kg refillable cylinder, Up Aqua inline atomizer, 300 bpm; injection starts 2 hours before lights on and end 1 hour before lights off; water surface agitation is weak; I have a fine and uniform mist of CO2 in whole tank
-plants: echinodorus, hygrophila polisperma, pogostemon quadrifolius, ludwigia repens; only 50% of bottom is planted, will add more plants later
-fishes: 6 angelfish, 4 cory, 6 sae
-tap water: pH=7.2, KH=2dKH, GH=2.14dGH
-tank water: pH=6.6 (measured with drops, after soil was added, without CO2), KH=1dKH, GH=5dGH (Sera Mineral Salt used to increase)
-fertilization: EI for low light/weekly; macro - KNO3, K2HPO4, K2SO4, micro - EL Profito, targets - NO3=10ppm, PO4=1ppm, K=10ppm, Fe=0.1ppm

And now, some things that I want to clarify, and I need a little help:
-according to https://rotalabutterfly.com/co2-ph-calculator.php, to obtain 30 ppm CO2, target PH (at KH=1) is 6.00; is this pH target correct or pH should be 5.6 (1 drop from actual pH lowered by soil)?
- in case the pH is not ok at lights on or not constant during lighting period, it is better to play with bubble rate or surface agitation to fix that? or maybe both?
- it is "mandatory" to have more that 70% of bottom planted to have the right/constant amount of CO2 in water?
- I consider my lighting as low level (2600 lumens for 135 L of water); is this fine or can be considered medium lighting?

Thanks in advance!
 
First you measure tank water before CO2 than whith CO2 on every hour. You should try to get a 1 point drop. Drop should happen in one-max 2- hour. PH should remain about constant during lighting period ( about 6 hours, then it can raise again.
Measure some tank water which has been out for 12-24 hour ( degassed) this should be around where your pH is before CO2 on. If there is a significant pH drop from degassed to tank water then you should think about aeraiting during the night. Only use surface agitation to loose CO2 if fish are gasping.
It's not plants that dictate CO2 it's light levels.
Sadly lumens wont let us comment on light values, that's a human measure not a plant measure (PAR is a plant measure). Plants will tell if they are getting enough CO2 for that light:oops:
 
-tank water: pH=6.6 (measured with drops, after soil was added, without CO2), KH=1dKH, GH=5dGH (Sera Mineral Salt used to increase)
-fertilization: EI for low light/weekly; macro - KNO3, K2HPO4, K2SO4, micro - EL Profito, targets - NO3=10ppm, PO4=1ppm, K=10ppm, Fe=0.1ppm

And now, some things that I want to clarify, and I need a little help:
-according to https://rotalabutterfly.com/co2-ph-calculator.php, to obtain 30 ppm CO2, target PH (at KH=1) is 6.00; is this pH target correct or pH should be 5.6 (1 drop from actual pH lowered by soil)?
Hi,
Yes you are on the right path. The target pH is inexact because of the acids and bases in the tank water and because of their interaction with sediment and hardscape. If the "natural pH" of the tank is 6.6 then the target pH should be around 5.6. It's not really necessary to be exact and if you use a dropchecker then you will be able to see the color change which will help to avoid injuring the fish.

- in case the pH is not ok at lights on or not constant during lighting period, it is better to play with bubble rate or surface agitation to fix that? or maybe both?
Both methods should be used. It requires trial and error to get the best performance.

- it is "mandatory" to have more that 70% of bottom planted to have the right/constant amount of CO2 in water?
No, there is no mandatory amount. It's just a good idea to have a lot of plants in order to help stabilize the tank chemistry.

- I consider my lighting as low level (2600 lumens for 135 L of water); is this fine or can be considered medium lighting?
Everyone assume their lighting is low, but unless you actually measure it with a PAR meter there is no way to tell - until algal blooms occur.

Cheers,
 
Last edited:
Thanks for replies!

I didn't had enough time for full pH profile, but I have some updates.

pH before CO2 on: 6.5
pH at lights on: 6.1
pH at lights off: 5.9

After few hours from CO2 on, my drop checker is light-green/yellow.

It seems that too much CO2 is injected. I'll decrease the bubble rate, while keeping an eye on DC.
 
Pre pH is best done by taking a glass of water out of tank and weighting 12-24hrs to see what the base line pH is as the water doesnt always completely degas of CO2.
DC colour change is good way to tell [CO2] at end of CO2 period if the pH is stable, yours has a 0.2pH drop from lights on till lights off which isnt bad but not ideal. I call mine to stable when its within 0.1pH between lights on till CO2 off
 
After 24h pH is 7.2 (same as tap water). That's why I said that CO2 is too much and I'll decrease the bubble rate (maybe I'll obtain pH 6.2 at lights on and will remain constant during lighting period).
 
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