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What is the cheapest way to get PH down??

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pH is extremely important in aquaponics.  Just like with temperature, most living things have a very specific pH range in which they can survive, and an even narrower range in which they thrive.  In aquaponics, there are four living things co-habiting the same eco-system so you want the pH of your water in a range that is compatible with all four: your fish, your plants, the worms and the bacteria.  For fish, this is optimally a pH of around 6.5 to 8.0. For plants, this is a pH of around 5.0 to 7.0.  For red worms and for bacteria it is a pH of 6.0 to 8.0.  Aquaponic systems are a compromise of the pH requirements of all four components. Thus, optimal pH is around 6.8 to 7.0. This is okay for the fish (as it protects against ammonia toxicity), is okay for the plants (as it allows them to take up the nutrients they require for growth) and is good for the red worms and bacteria.
Sylvia is exactly right on the importance of pH. Your 50% pea gravel mix may keep the pH up more than normal. I have one system that is all pea gravel and the pH has always stayed in the mid 7s but the systems that are mostly hydroton do not.

Not all pea gravel is the same.  Pea gravel is really only describing size/shape.

You need to find out what the rock is made of.  Quartz/granite type river rocks if washed before use will not affect pH long term while limestone or marble will keep pH way too high for most plants to be very happy.  Diatomite may cause pH to drop too low if not buffered and monitored closely.  Some kinda of Silica can cause low pH too.  Many of the manufactured (heated) expanded clay/shale will have oxides on them from the manufacturing and need to be rinsed well before they will stop affecting pH(bringing it up.)

Hydrochloric acid at a pool store. Mix it 10 parts water to 1 part acid. Then add it to your tank in 5 ml increments until your pH is where you want it. My plants thrive at 6.6-6.8 pH the tilapia are growing like mad. 7.0-7.2 was too high and the plants did poorly. pH is the key to happy plants. :D

thanks everyone, I use mostly pea gravel now and add the muriatic acid once in awhile.

Hi Litano

The biggest benefit to having your pH in 6s is the availability of fe2 for your plants commonly referred to as "chelated" iron for dirt farming.  When the pH is above 7.0 the iron turns fe3 commonly known as rust or iron oxide which is unavailable for plant uptake.  If your leaves turn yellow, bump your pH down a few notches. 

Check your gravel by pouring acid (vinegar, lemon juice, pool acid, etc) on the media to see if it foams/bubbles, if it does, you have a limestone based media and it will drive your pH up constantly.

Never use the citric acids as they play havoc with system.  Here in Arizona our water supply is around 8.2 pH and we all use pool/muratic acid to control the pH.  For a 500 gallon fish pond, I'm using 8 oz mixed into 5 gallons of water and then slowly metered into the sump while the pump is running over a 1/2 hour period.  I made 3 - 1/8" holes in the side of the 5 gallon bucket for metering into the sump.  A local fellow AP gent, killed his fish/system by dumping the entire 5 gal bucket of mix into his 200 gallon pond, so be careful and go slow.  Patience is important when your babies lives are at stake. 

all the best,

Jim

Hi Jim, thanks again for your good thoughts. Where in AZ. are you? I have a friend in Cottonwood whom is interested in aquaponics. I have 15 ebb and flow grow beds, and one of the bell siphons stopped working and flooded the bed. I then wondered why not just let the water flow over the stand pipe and it would just be like a raft system. What would be the difference? Would it work? LLoyd

Yep please be careful when adjusting the pH down with acid.  It is best if you can adjust a container of your top up water down to the desired pH and let it settle and then use the adjusted water to top up the system rather than actually trying to use acid directly in an AP system.  If you adjust the pH too much in too short a time, you can really mess things up.  You don't want the pH to move more than about 0.2 per day.

Collecting rain water can help bring pH down.



litano said:

Hi Jim, thanks again for your good thoughts. Where in AZ. are you? I have a friend in Cottonwood whom is  I have 15 ebb and flow grow beds, and one of the bell siphons stopped working and flooded the bed. I then wondered why not just let the water flow over the stand pipe and it would just be like a raft system. What would be the difference? Would it work? LLoyd

 

Ebb & flow... with bell siphons??

 

Do you mean "flood & drain".... if so then removing the bell.. and just letting the water flow over the standpipe... what's called "constant flood".... will work perfectly well... as long as your system is oxygenated sufficiently

OPPS. YES, FLOOD AND DRAIN. I may try leaving one of the five grow beds without the bell, maybe the one with lettuce. thanks..

Hi Litano:

I'm in the Phoenix metro area, a little burg called Scottsdale.   Your friend is welcome to come check my system out.  Cottonwood is in a big, deep river valley near the beautiful red rocks of Sedona.  It is a nice place to live climate wise, just about snows and gets hot enough to know it's hot; it will be great for aquaponics.  An acquaintance of mine owns their water supply company.  Friend me and I'll send my contact info for your buddy.

Bell siphon...

I have turned my 4x8 raft bed into a bastard system at best.  I have two standpipes, one about 2.5" high, it sets the minimum depth and the other about is 8" high and is about the max depth.  The pump runs about 30 minutes per cycle, it takes about 20 minutes to fill to 8".  So the max depth is seen for about 10 minutes per cycle.  I run the pump every hour during daylight hours and every three hours in the dark this time of year.  I change the dark hours cycle times in the winter when the high temps are below 75f (brr) to completely off overnight as I heat the pond water by circulating it in a solar collector all day; DO2 never seems to be an issue.  I don't use rafts anymore.  I have everything growing in cut off 2 liter soda bottles filled with media.  The water flows in and out through 1/4 holes near the base of the pot.  Mosquito fish and duckweed fill in the spaces nicely.  Different but it works well, very easy to plant, maintain and harvest, just pull the plant out and work with the pot on the planting bench and put it back. 

tell your friend I know several people with "standard" AP systems and know of an AP class in Tempe every couple of months, next date is coming up soon.

The best part about AP is ...There are no rules! 

all the best,

Jim

Hey, thanks for the offer. Do you have videos of your systems? I will tell my friend in Cottonwood of your kind offer. How do I friend you? 

Jim Troyer said:

Hi Litano:

I'm in the Phoenix metro area, a little burg called Scottsdale.   Your friend is welcome to come check my system out.  Cottonwood is in a big, deep river valley near the beautiful red rocks of Sedona.  It is a nice place to live climate wise, just about snows and gets hot enough to know it's hot; it will be great for aquaponics.  An acquaintance of mine owns their water supply company.  Friend me and I'll send my contact info for your buddy.

Bell siphon...

I have turned my 4x8 raft bed into a bastard system at best.  I have two standpipes, one about 2.5" high, it sets the minimum depth and the other about is 8" high and is about the max depth.  The pump runs about 30 minutes per cycle, it takes about 20 minutes to fill to 8".  So the max depth is seen for about 10 minutes per cycle.  I run the pump every hour during daylight hours and every three hours in the dark this time of year.  I change the dark hours cycle times in the winter when the high temps are below 75f (brr) to completely off overnight as I heat the pond water by circulating it in a solar collector all day; DO2 never seems to be an issue.  I don't use rafts anymore.  I have everything growing in cut off 2 liter soda bottles filled with media.  The water flows in and out through 1/4 holes near the base of the pot.  Mosquito fish and duckweed fill in the spaces nicely.  Different but it works well, very easy to plant, maintain and harvest, just pull the plant out and work with the pot on the planting bench and put it back. 

tell your friend I know several people with "standard" AP systems and know of an AP class in Tempe every couple of months, next date is coming up soon.

The best part about AP is ...There are no rules! 

all the best,

Jim

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