Quick But Important Ph Question

[sophos9]

My electronic PH tester turned up and is ace so I get to work making sure I have a 1PH drop to equal 30ppm

Tap water is 7.8 so I target and hit 6.8PH. I then wonder if there is anything else that could affect PH so I take a sample of tank water and leave it out for 40hrs to ensure all CO2 is dissolved

The water from the tank measures 8.2PH!!!! So I presume I should be targeting 7.2PH to hit 30ppm?

 

[sophos9]

This test has just been confirmed with a color test kit

Anyone?

 

[Themuleous]

Yes thats right, you need a 1pH point diff between the standing water and the tank water, NOT your tap water. As you have found there can be a big difference.

Sam

 

[sophos9]

Sam, Hi

Thanks for the quick reply. Yep, this explains a lot, will adjust the CO2 and put this down to a learning experience! Good things these PH testers!

 

[Themuleous]

Indeed they are happy to help

 

[JamesC]

You have to be careful with doing the 1pH drop method and understand it's limitations. It all relies on the presumption that standing water with have 3ppm CO2. This in reality isn't normally the case. If your standing water has 2ppm CO2 then a 1pH drop will mean there is 20ppm CO2 in the tank, also at 4ppm this will equate to 40ppm. The drop checker with 4KH reference solution is by far the best method currently available.

James

 

[sophos9]

James, Hi

Just so I understand, does the 4KH reference solution depend on the water being 4KH? What happens if the tank water is 3 or 5KH?

 

[JamesC]

As the 4KH reference solution in the drop checker doesn't come in contact with the tank water it doesn't matter what the KH of the tank water is. This is the beauty of using the drop checker method.

James

 

[sophos9]

Ahhh.... got it!!

My drop checker with 4KH reference goes light green at 6.8PH, tap water is at 7.8 and water left out of the tank for 24hrs is at 8.2

Do you think that dropping 1.4PH is OK

 

[JamesC]

Do you think that dropping 1.4PH is OK

That could well be right. If you tank water that has been left for 24 hours has a CO2 level of 1.2ppm, then a 1.4 pH drop would give you 30ppm CO2 - spot on!!

It is very hard to know what the ppm level of CO2 is in standing water and is dependant on where you live and atmospheric conditions.

James

 

[sophos9]

James, to be fair the water was left out for more like 40hrs....

I've lost trust in the drop check since my SERA live tester would never go light green (despite hitting 74ppm and losing 1 Otto) I have bought a glass one from Aquatic Magic with 4KH reference although I may be 'tapping up' Mr Spencer for some of his lifetimes supply

So trust the drop check hey...

 

[JamesC]

I never used to bother checking the CO2 levels much. I just went by how the plants were growing and so knew that CO2 was good. If I thought there was something amiss then I'd check the pH which I always kept at 6.2. I have brought an ADA drop checker partly out of curiousity but also because it is such an easy way to monitor levels.

James

 

[amagphoto]

Ahhh.... got it!!

My drop checker with 4KH reference goes light green at 6.8PH, tap water is at 7.8 and water left out of the tank for 24hrs is at 8.2

Do you think that dropping 1.4PH is OK

Just reading your posts and I'm dealing with the same kind of thing....have a 55 gal fresh planted tank, kh 9 from test kit, ph 6.6, trying to make sure what my Co2 levels are, (have a Red Sea pressurized co2 system) and use the uspide down drop checker with solution in it) Question....is this in tank monitor same as "drop checker" you are talking about. It shows green when at its optimal co2 level in tank, but I'm reading kh 9 ph 6.6 so when I use the chart method it's showing too high co2 levels. What is the best way to measure co2??? Help!!