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I am having a problem lowering my PH level.  It is currently at 8.4 which is way to high. Alkalinity is high also ( Test strips say 300ppm+).  These are parameters that come out of my tap water.  My city gets their water from an underground aquifer.  

I have been adding Muriatic Acid and it will drop to 8.2 - 8.3 but the next day it is back up 8.4.  I am slowly adding the acid as I have fish in the FT and I have been doing this for three days now with no luck.  Any suggestions would be appreciated to fix my high PH.  My plants are suffering because of nutrient lock out.

Set Up- Running for about 5 months

4000g Fish Tank w/ 100 channel cats 4-6"

Grow Bed - 1 - 8'x4'x12" grow bead with crushed granite. (in process of building more)  I have tested the granite with vinegar and no bubbles.

Fish Tank Levels

PH - 8.4

KH - 300ppm+ (Alkaline)

GH - 25ppm (Soft)

Nitrate - 20mg/l

Ammonia - 0

Nitrite - 0

Thanks in advance,

Jason

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It sounds like the water you are getting from the city is high in alkaline. this is like having a block of coral in your system.  you will need to add in an equal part acidity to neutralize the alkalines. (you have about 1.2 gallons of alkaline in your system just floating around) so the neutralize(remove) from your system you would need 1.2 gallons of acid. but DO not do this it will hurt your system. you are on the right track adding in small portions at a time, I would go from a dropper to about 2/3 cup  everyday (broken up 1/3 morning and 1/3 evening) for 2 weeks. (watch your levels closely test before every application skip any application if levels are  low) stop adding in once its close and let it stabilize. also filter your water source. to avoid adding in more alkaline prolonging the time it takes to lower. in theory this in an exact science but application is not. you want the water to lower slowly to avoid shock to fish and plants. you want about 2 weeks but longer is better then shorter.

the good news if your water source is the cause of the alkaline if you ever need to raise your PH ust add in unfiltered water.

once your PH is stable at 7 you alkaline should be at or close to 0ppm.

to test before doing in system take 50 gallons out of your system and add in 0.24 cups of the acid you are using, let sit with air stone in it.and test the next day. your ph should be 7 and alkaline should be 0ppm (in theory)

Thanks for the information Michael!  From what you have stated I am on the right track.  I have been dosing the acid at 4 ounces ( a little more than a 1/3 cup)  in the morning and 4 in the evening for the past week.  I have added a little over a qtr of the gallon bottle of acid total. I am now down to 8.1.  It is slowly working its way down and the fish seem to be doing fine. I can tell the nutrients are starting to unlock as my plants are starting to grow again and look better.

Thanks for all your help!  Its really appreciated!



Michael Silberstein said:

It sounds like the water you are getting from the city is high in alkaline. this is like having a block of coral in your system.  you will need to add in an equal part acidity to neutralize the alkalines. (you have about 1.2 gallons of alkaline in your system just floating around) so the neutralize(remove) from your system you would need 1.2 gallons of acid. but DO not do this it will hurt your system. you are on the right track adding in small portions at a time, I would go from a dropper to about 2/3 cup  everyday (broken up 1/3 morning and 1/3 evening) for 2 weeks. (watch your levels closely test before every application skip any application if levels are  low) stop adding in once its close and let it stabilize. also filter your water source. to avoid adding in more alkaline prolonging the time it takes to lower. in theory this in an exact science but application is not. you want the water to lower slowly to avoid shock to fish and plants. you want about 2 weeks but longer is better then shorter.

the good news if your water source is the cause of the alkaline if you ever need to raise your PH ust add in unfiltered water.

Happy to help

Michael or Jason,

I know this is a very old thread but how did this turn out?  I have a much smaller system but dealing with similar issues.  

250 Gallons

50 Tilapia

4 Growbeds and 40 netpots

My KH is at 240 GH 180 and PH 8.5.   

I guess I would like to know how much alkalinity I have in my system and how you equated that to gallons, in order to balance with the acid.   

Thanks for any help on this.

Spencer

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