What is the best way to lower the GH

[David Waite]

Hello Aquapons, My GH is off the scale. My PH is holding at 7.6 to 7.8 Cant seem to move it lower with acid. Using Nylons with peat to try and help. Any Ideas. The KH is at 125ppm as well.

[RupertofOZ]

P.S ... other than when washing your clothes... don't worry too much about gH....

 

The magnesium and calcium ions are beneficial for plant growth.... unforunately... the kH and resulting pH... may often mean that the plants can't uptake them well....

[David Waite]

Rupert thanks for the very detailed break down. I do have a ph of 8.4 water source and will condition the water with muratic in 5 gal pails before I add it. Question? I was adding about 10 ounces every third day and watching the ph fall consistently to 7.6 to 7.8 ph. I then added 20 more ounces and the ph did not move. How much is to much acid before I should consider a RO water softner on source water going in to tank. Like earlier stated gh is over 225 ppm and kh is 125ppm. My system is 1000 gal or 3750 liters for you kangaroo riders. hehe.

[jrtroubleshooter]

Hydrochloric acid is no go with plants due the CL

[RupertofOZ]

With fish present, you shouldn't move pH more than 0.4 at any one time... remember pH is logarythmic... a change from 8.4 to 7.4 is an eqivalent to a tenfold increase in acidicy...

 

Forget about an RO softner.... gH is not a concern, or a problem... an RO unit will soften the water... ie remove metalic ions, thus lessening the gH.... but wont affect the carbonate hardness kH...

 

Treat your top up water... if you feel the need to treat the tank itself... then just add small quantities each time... and don't expect to see the pH drop... until the carbonate buffer is exhausted...

 

David Waite said:

Rupert thanks for the very detailed break down. I do have a ph of 8.4 water source and will condition the water with muratic in 5 gal pails before I add it. Question? I was adding about 10 ounces every third day and watching the ph fall consistently to 7.6 to 7.8 ph. I then added 20 more ounces and the ph did not move. How much is to much acid before I should consider a RO water softner on source water going in to tank. Like earlier stated gh is over 225 ppm and kh is 125ppm. My system is 1000 gal or 3750 liters for you kangaroo riders. hehe.

[RupertofOZ]

The amount of Cl ions dissassociated due to using hydrocloric acid to combat carbonate buffer is minimal... and wont affect the plants unless the system is already salted to levels above 2-3ppt...

 

Chlorine is necessary in plants for osmosis and ionic balance; it also plays a role in photosynthesis.

 

Cl ions are also benifical to fish in terms of osmotic regulation, slime coat production, and mitigating against nitrite poisoning...

jrtroubleshooter said:

Hydrochloric acid is no go with plants due the CL

[David Waite]

Rupert really like the fact I dont need to worry about gh. I will only concern myself with Kh and ph. I will continue to use acid in small doses to bring the ph down. From what I gather the acid just needs to exhaust the Kh buffer then I should see the ph continue to lower. I like the fact that the system will do some of  this on its own. Importing water is just a pain in the ass if you know what I mean. what I have gathered from the gurus above is be patient and add acid slowly. Work with the water I have. Much thanks gents................D

[TCLynx]

Once your system reaches a point in the cycling, you will no longer need to worry about adding acid to the system itself and you will only need to worry about the kH of the top up water and over time you might even need to let more of that kH into the system to keep the pH from dropping too low but this will take a while and it will also vary depending on time of year and how heavily the fish are pushing your biofilter. 

 

When my fish push my biofilter hard in summer my pH in my big system has even dropped as low as 7 (and that system is using shells as 40% of it's media so the pH is naturally buffered to 7.6)

[David Waite]

This discussion really taught me and Im sure a whole bunch of fish huggers water science 101. Much thanks again.

[Robin]

this is really useful, Rupert. now I just need a friendly science nerd to draw me a diagram!

robin

[heidi critchfield]

I am having the same problem. We put in a tank two days ago to collect rainwater and hope to be able to solve the issue in that way. I tried the peat bags and gallons of vinegar. When it rained I kept hoping for a lower balance, but never had enough to keep from adding my well water and ruining the whole thing! Grr... then went to muriatic acid two days ago. The fish aren't eating much, so dropping the pH may have stressed them. We will see over the next little while. Good luck and keep posting updates with what you find. This is my biggest problem. The high pH causes weakness in the plants and they become diseased. It is so troubleing. My system has been in place since May or so and every time we add water it ruins the balance. The rain catch should solve it ...I wish I had seen this forum before I got desperate and lowered the pH so much. I hope my poor tilapia survive!

 

 

[TCLynx]

If you must add well water and need to use acid to bring down the pH, I would recommend having a separate container to adjust the pH in and let it settle before adding it to the system.  Adding acid directly to a system is not the best way to go about it since it is really easy to mess up the dose.

[Harold Sukhbir]

Hi Rupert,

 

Rupert : "Forget about an RO softner.... gH is not a concern, or a problem... an RO unit will soften the water... ie remove metalic ions, thus lessening the gH.... but wont affect the carbonate hardness kH..."

Harold : "Are you sure about Reverse Osmosis not reducing the KH of water? I've read that RO units will strip the Carbonates and a host of other nutrient from water and alter both KH and GH"

RupertofOZ said:

With fish present, you shouldn't move pH more than 0.4 at any one time... remember pH is logarythmic... a change from 8.4 to 7.4 is an eqivalent to a tenfold increase in acidicy...

 

Forget about an RO softner.... gH is not a concern, or a problem... an RO unit will soften the water... ie remove metalic ions, thus lessening the gH.... but wont affect the carbonate hardness kH...

 

Treat your top up water... if you feel the need to treat the tank itself... then just add small quantities each time... and don't expect to see the pH drop... until the carbonate buffer is exhausted...

 

David Waite said:

Rupert thanks for the very detailed break down. I do have a ph of 8.4 water source and will condition the water with muratic in 5 gal pails before I add it. Question? I was adding about 10 ounces every third day and watching the ph fall consistently to 7.6 to 7.8 ph. I then added 20 more ounces and the ph did not move. How much is to much acid before I should consider a RO water softner on source water going in to tank. Like earlier stated gh is over 225 ppm and kh is 125ppm. My system is 1000 gal or 3750 liters for you kangaroo riders. hehe.