Heya 
I live in Austin, Texas and our water is very high pH. I think mainly due to the fact that it comes from the Colorado River here, which runs over a bunch of limestone as winds it's way through central Texas. I've tested the water down at the river (1 mile away) and from my tap... they both come out 8.5+ pH (hell it could be close to 9. pH but it's hard to tell with my droppy, shakey, match the color game system.)
So the...
General Hardness 10 degrees
Carbonate Hardness 6 degrees
I've got fish (all sunfish) that came from the Colorado so they don't have a problem with the pH, but my system is an aquaponics system (http://www.monsterfishkeepers.com/forums/showthread.php?t=121390). That means I don't have a regular filter. The filter for my 300 gal. tank/pond is 150 gal. of gravel filled with plants. Basically it's a hydroponic system that uses dirty fish water as nutrient and then returns clean(er) fish water back into the system. This works great for ammonia, nitrite, nitrate control. I've had my tank set up for a few months now. I don't do any water changes, I just top off water lost due to evaporation and plant uptake. Ammonia, Nitrite, Nitrate all 0.0 mg/l.
Here's my problem. While this water may be suitable for my fish 8.0+ pH water makes it hard for plants to take the nutrients out of the water. I'd like to get the water down to 7.6 pH, this will make all the nitrogen and other trace elements readily available to plant consumption.
What I've done so far is dilute 1 cup of vinegar in a a 55 gal. barrel which brought the barrel water went to 5.0 pH, or lower but that was the low end of my pH kit. I then slowly (over the course of a few days) added the the low pH water to my system. I brought my systems pH down to 7.6-7.8 pH. I'll take it if it's stable.
So now in the mornings my system will start off with 7.6-7.8 pH and then steadily climes throughout the day up to 8.1-8.2 pH by the end of the day. I do have a little algae bloom going on as the stock tank is buried in the ground outside. I've build a gazebo type cover to keep a lot of the sun off of it. The way I understand it the algae will take up CO2 during the day, removing carbonic acid so that pH goes higher. At night the algae respirates and takes up O2 and releases the C02 back into the water where it turns back into carbonic acid, thus lowering the pH again.
I don't think the fish enjoy this pH shift every day. My plants get 8.1+ pH water during the sunlight hours when they should be taking up nutrients. At night the pH drops back down closer to the 7.6 pH they actually want, but I'm guessing it's the wrong time of day for that.
So... do I have this correct for the most part?
What steps can I take to keep my pH closer to 7.6? (more shade to get rid of all the algae? will a pond cover plant like duckweed work or will it respirate just like the algae, causing pH shifts?)
When I top off the water I'll be reintroducing 8.5+pH water to my system. Is it ok for me to figure out how much vinegar it takes to bring this down to 7.6 pH then add the water?
Oh well, just looking for some suggestions and making sure I'm on the right track.
Thanks yall!
Oh, one last thing... I've read that some municipalities take CO2 out of the water to try and keep the carbon content down as it goes through the pipes (to keep it from building up in the pipes?). This will raise the pH but when you aerate it replaces the CO2 and the pH will go back down. I don't use airstones in my system. I've got a 900 gph pump on my 300 gal. tank, the water runs over 150 gal of gravel and comes out the other end at about 6mg/l O2. So, I assume the water's being sufficiently oxygenated/aerated .... ?
I live in Austin, Texas and our water is very high pH. I think mainly due to the fact that it comes from the Colorado River here, which runs over a bunch of limestone as winds it's way through central Texas. I've tested the water down at the river (1 mile away) and from my tap... they both come out 8.5+ pH (hell it could be close to 9. pH but it's hard to tell with my droppy, shakey, match the color game system.)
So the...
General Hardness 10 degrees
Carbonate Hardness 6 degrees
I've got fish (all sunfish) that came from the Colorado so they don't have a problem with the pH, but my system is an aquaponics system (http://www.monsterfishkeepers.com/forums/showthread.php?t=121390). That means I don't have a regular filter. The filter for my 300 gal. tank/pond is 150 gal. of gravel filled with plants. Basically it's a hydroponic system that uses dirty fish water as nutrient and then returns clean(er) fish water back into the system. This works great for ammonia, nitrite, nitrate control. I've had my tank set up for a few months now. I don't do any water changes, I just top off water lost due to evaporation and plant uptake. Ammonia, Nitrite, Nitrate all 0.0 mg/l.
Here's my problem. While this water may be suitable for my fish 8.0+ pH water makes it hard for plants to take the nutrients out of the water. I'd like to get the water down to 7.6 pH, this will make all the nitrogen and other trace elements readily available to plant consumption.
What I've done so far is dilute 1 cup of vinegar in a a 55 gal. barrel which brought the barrel water went to 5.0 pH, or lower but that was the low end of my pH kit. I then slowly (over the course of a few days) added the the low pH water to my system. I brought my systems pH down to 7.6-7.8 pH. I'll take it if it's stable.
So now in the mornings my system will start off with 7.6-7.8 pH and then steadily climes throughout the day up to 8.1-8.2 pH by the end of the day. I do have a little algae bloom going on as the stock tank is buried in the ground outside. I've build a gazebo type cover to keep a lot of the sun off of it. The way I understand it the algae will take up CO2 during the day, removing carbonic acid so that pH goes higher. At night the algae respirates and takes up O2 and releases the C02 back into the water where it turns back into carbonic acid, thus lowering the pH again.
I don't think the fish enjoy this pH shift every day. My plants get 8.1+ pH water during the sunlight hours when they should be taking up nutrients. At night the pH drops back down closer to the 7.6 pH they actually want, but I'm guessing it's the wrong time of day for that.
So... do I have this correct for the most part?
What steps can I take to keep my pH closer to 7.6? (more shade to get rid of all the algae? will a pond cover plant like duckweed work or will it respirate just like the algae, causing pH shifts?)
When I top off the water I'll be reintroducing 8.5+pH water to my system. Is it ok for me to figure out how much vinegar it takes to bring this down to 7.6 pH then add the water?
Oh well, just looking for some suggestions and making sure I'm on the right track.
Thanks yall!
Oh, one last thing... I've read that some municipalities take CO2 out of the water to try and keep the carbon content down as it goes through the pipes (to keep it from building up in the pipes?). This will raise the pH but when you aerate it replaces the CO2 and the pH will go back down. I don't use airstones in my system. I've got a 900 gph pump on my 300 gal. tank, the water runs over 150 gal of gravel and comes out the other end at about 6mg/l O2. So, I assume the water's being sufficiently oxygenated/aerated .... ?
).
So I put the CO2 hose into a 2" long piece of 1" diameter pipe stuffed with rockwool. The CO2 passing through the rockwool breaks the bubbles up very finely, more so then the air stone I tried.