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pH drop / pH profile

J

jwmachon

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Hi

So done plenty of reading around pH profile ag the 1 point pH drop

However I see people take the 1 point from tank water before lights on and others take it from tank water thats been sat for 24-48 hours

The difference between them both is considerable

So which do you actually use or is it mixed opinions
 
jwmachon said:
However I see people take the 1 point from tank water before lights on and others take it from tank water thats been sat for 24-48 hours
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Some people will indedd take the ph reading of the tank water just before the Co2 turns on, and drop it 1 point. This is acceptable if said person is confident their tank water is fully degassed of any added Co2. It's a risky business, some might say living life on the edge, one who likes to throw caution to the wind e.t.c

If you are chasing a 1 point drop do it from tank water that's been sat for 24hrs and degassed.
 
Also some people aim for a higher pH drop (from a degassed sample), so using a 1 pH drop from the partially degassed sample taken from the tank before lights are on could be equivalent to a higher, still reasonable, pH drop.
 
I use tank water I’ve degassed for two days. I usually will stir it a couple times to help with diffusion.

I do think a 1 ph drop is often not enough depending on how much light you are using. Under very high light I would suggest targeting at least 1.3 ph drop and then slowly keep increasing till you notice any stress with your livestock.
 
Depending on alkalinity, one point pH drop may refer to pretty variable amount of CO2. Are you aware of that?
 
I need to submit this question
I have a very very acelareted high luminosity planted tank... 90% full planted with fast growing demanding Steem plants. I already learned not to messure but to real the plants... but I need to dose 20 - 25 ppm nitrate (as kno3)for my plants to be fine. Is it normal to need all this nitrate ? Some plants like macandra or nasaea dont like this heavy fertilization. My kh is 3 and i bring my ph from 7 degased to 5.7 according to fish confort. Obviously the lower i get the more n03 and micros that my plants demad (paling)... and i consider this leves of nitrates and micros to be exagerated and unhealthy for fish and some plants. If i lower the lights, plants like ludwigia inclinata, prosespinaca, furcata etc.. inmidiatly deteriorates. If i use les co2.. say ph 6... will this be dagerous? Can i be using TOO MUCH c02 ? My fish are fine though.
I am in honduras, and been for more than 10 years in the hobby.. before.. was some 8 years in industrial hidro/aquaponics.
 
_Maq_ said:
Depending on alkalinity, one point pH drop may refer to pretty variable amount of CO2. Are you aware of that?
Click to expand...
To expand on Maq's point the absolute value also depends on the starting and ending pHs.

At a low alkalinity of say 1kH, Dropping 1pH from 8.5 to 7.5 is an increase in CO2 concentration of 0.8ppm. Dropping from 7.5 to 6.5 would be an increase of 8.6ppm. At an alkalinity of 19 dropping from 8.5 to 7.5 is an increase of 12.5ppm and from 7.5 to 6.5 is 165.9ppm

However the proportional value doesn't 10x as much CO2 for 1pH drop. Assuming degassed water is at 3ppm CO2 a 1pH drop from there will be 30ppm CO2, which is where the 1pH drop from degassed water comes from.
 
_Maq_ said:
More info (+ pics) on your tank would be useful, but the volume of nitrate you indicate is definitely extreme.
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700 lt. 60 cms depth, soilbased 10 cms substrate at front, 25 times per hour turnover, more than 1.5 wtt/lt full spectrum Led at 60 cms from substrato, pressurized c02 with 2 inline reactors, Milwaukee ph controler droping down to 5.7 (7 degased), kh 3. Gh 6. Daily 10% waterchange and 30% weekly. automated dosing daily macros and GLA edta micro mix. 80% full planted with: ludwigias inclinata, pantanal, red rubin, atlantis, lymnofilia aromatica, pogostemun stellatum, proserspinaca, c. Furcata, m. Tuberculatum, ambulia, carimbosa, rotalas rotundifolia, macandra, heterantera zosterifolia, etc..
I have read Tom Baar using 80 ppm nitrate and 8 ppm phosphate in his aquarium
 
20 ppm nitrate (40 ppm kno3) is what i need to dose daily for my plants to be fine..
But obviously fish dont like it, sensitive plants like macandra or nasaea gold dont like it. I realy have to be on top of it and change water frequently.
 
20ppm Nitrate in 700L of water is 14 grams of Nitrate per day (nearly 28g of Kno3) ? Given nitrogen is used to make proteins which are only 16% nitrogen and 22% of Nitrate is Nitrogen that's 20g of Protein growth in your plants per day. That's a lot.

Can we see a picture of the tank? With a huge fast growing jungle you might have that high a need. Do you test NO3 at the end of the week to see your accumulation? If it were me with that high a volume I'd be very concerned that if any plant went slightly dormant for some reason I'd be accumulating dangerous levels.
 
Rafael pinel said:
20 ppm nitrate (40 ppm kno3) is what i need to dose daily for my plants to be fine..
But obviously fish dont like it, sensitive plants like macandra or nasaea gold dont like it. I realy have to be on top of it and change water frequently.
Click to expand...
As I posted above, ever thought of dosing some Urea Prills?
 
LightingBamboozled said:
To expand on Maq's point the absolute value also depends on the starting and ending pHs.

At a low alkalinity of say 1kH, Dropping 1pH from 8.5 to 7.5 is an increase in CO2 concentration of 0.8ppm. Dropping from 7.5 to 6.5 would be an increase of 8.6ppm. At an alkalinity of 19 dropping from 8.5 to 7.5 is an increase of 12.5ppm and from 7.5 to 6.5 is 165.9ppm

However the proportional value doesn't 10x as much CO2 for 1pH drop. Assuming degassed water is at 3ppm CO2 a 1pH drop from there will be 30ppm CO2, which is where the 1pH drop from degassed water comes from.
Click to expand...
I have to say, I really hate this whole "pH drop" concept. You know you can get a great read on actual dissolved CO2 without needing to make any assumptions by using a drop checker, so why invite complications? You can't really interpret what a pH drop means in real terms unless you know with reasonable accuracy what your KH and pH are and neither of these are trivial to measure accurately and figuring out what maths to do on them to get your answer also has potential pitfalls.
 
Andy Pierce said:
You know you can get a great read on actual dissolved CO2 without needing to make any assumptions by using a drop checker, so why invite complications?
Click to expand...
Because drop checkers take multiple hours andaren't always easy to read (shiny glass reflecting green plants is a bugger when seeing where from blue to yellow the liquid inside is). pH and kH tests take seconds, and can be read easily. That's the reason that sort of blunt instrument exists.

The drop checker is a great ongoing measure, but for setting up and making adjustments there's nothing quite like pH measuring.
 
Hi all,
As long term forum members will know I'm not, nor ever likely to be, <"a CO2 user">, so I have no practical experience, but I am pretty familiar with <"pH meters and pH measurement">.
Andy Pierce said:
You know you can get a great read on actual dissolved CO2 without needing to make any assumptions by using a drop checker, so why invite complications?
Click to expand...
@Andy Pierce 's point would be exactly the one I'd make. A drop checker, <"with 4 dKH solution"> and bromothymol blue narrow range pH indicator, doesn't have any moving parts, or anything that can go "wrong". <"CO2 Measurement Using A Drop Checker">

It is only CO2 that can diffuse across the air gap, the pH measured (<"by colour change">) is directly attributable to the amount of (formerly) dissolved CO2 that has diffused out of the tank water.

If your drop checker collects CO2 bubbles then it will read "high" (you have less CO2 then the drop checker indicates), but that is safer for your fish than relying on a pH meter, even a good one, which has <"multiple single points of failure">.

cheers Darrel
 
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