Can't seem to bring the PH down in my system please help!

[BenSD]

So in December of last year I switch from doing hydroponics to aquaponics. It has been a great experience and just to give a little introduction on my system below;

600 Square ft. Greenhouse

200 Gallon Tank (w/ Nile Tilapia who just started breeding!) 

About 40 Large Plants Hooked into the System and a lot of small ones in flood trays

So I have been battling to bring the PH down using buffer salts (forget the name, but they bond with CO2 to bring the PH down) and it really hasn't worked. I add some during the day when the PH is around 8.2 and it goes down to maybe 7.6 and then the next day its back up to around the same (with a little bit of different changes from time to time). 

I use tap water from La Jolla San Diego, which I treat with prime and have it in a large tank outside thats basically on demand (gravity fed) whenever I need to add water. The people at the fish store who seem to know what they're talking about, tell me its because of the buffers the city adds to the water that won't allow me to modify it. They told me all I can do is bring in my own RIO Water or install my own reverse osmosis system. Neither option I like as the greenhouse is down a hill on my property. Someone else told me adding Malaysian wood would maybe help, but a couple days on and no change.

Me messing with the PH has only really effected some goldfish I had in there (two of the three died), I removed the last and just removed my KOI also as I was concerned they would eat the Tilapia Fri I have just recently discovered in there. So now I dont want to move the PH too much as I am worried I may kill all those new little fish, but my plants are suffering! My cucumbers leaves look terrible and some fruit is aborting. My tomatoes have stunted growth and the fruit is either small or not making it from flower to fruit. 

If anyone has some advice, it would be really helpful! I know a lot of people say it just takes time, but I would kind of like to know if anyone has had any experience with bringing this down a little faster and saving mature plants!! Or how not to kill all my new little Tilapia, thank you!

[TCLynx]

I've heard that in South CA the tap water is like liquid limestone.  The tilapia probably think it's great.  But your plants won't.

You might be able to adjust the pH down in your top up water barrel using acid but that is only going to liberate too much calcium which could cause other problems.

The people at the fish store are probably right, and RO filter may be your own option.  Can you use an RO filter to fill up the barrel you use for topping up?

[Jan R. McNeil]

I have had problem.  you seem to have several problems.  you need 2 fish for every one fruit bearing plant and one fish for every 5 leafy green.  so you might not have your system established well enough to handle the plant load.  easy to fix add a bit of nutrients to your water, I use seaweed (worms way).  Second your pH.  you want to move your pH very slowly.  up and down like that is real bad on the fish.  don't need a die off..  to lower pH.  place peat in a panty hose...submerge under water ...make sure the water can pass by it well....I use a RV filter on my yucky city water.  I filter it into a 55 gallon barrel.  put a few cap-fulls of amquel (chloramane removal) and let the water sit for a bit.  try to collect rain water if you can  thats the best.

[BenSD]

Thanks for the advice, so it has kind of improved recently. I added a couple of things, some Malaysian driftwood, a reservoir system and a RO filter to help clean out that city water, and I used some chemicals to bring down the PH. It seemed to happened suddenly and looks like its sticking right around 6.5 PH. I do have a ton of plants in this system and probably not enough fish. I have maybe 10 pretty small Tilapia, who have already started breading, and about 7 tomato plants, 20 cucumber plants ranging in size and age, and a flood tray with a bunch of random things I am experimenting with. I wanted to expand, so I built another system that's not aquaponic, just regular hydroponic below and around it. The plants are doing substantially better than the ones hooked in with the fish. You said you had some luck with B. Seaweed, did it modify anything PH, nitrates, etc...? 

[Jan R. McNeil]

wow...I can't  get my pH that low....

          would a RO filter...I do not know about this filter

I looked it up in the manual Morning Star Fishermen manual  regarding pH   (MSF- is where I received my training"

• Tilapia can tolerate a wide pH range.
• Fish have average blood pH of 7.4
  • A desirable range of pH for fish would be close to that of fish blood, but Tilapia seem to do best at slightly higher pH of 8.3.
  • Fish become stressed if pH falls below 5 or rises above 10 due to a reduced capacity of fish blood to carry oxygen.
  Near-neutral or slightly acidic pH (7.0  to 6.0) is generally considered ideal for most plants.
• • In highly alkaline water, micronutrients such as iron, zinc, copper and manganese become chemically tied up and are sparingly available for plant use.
  • In highly acidic water, calcium, phosphorous, and magnesium become tied up and unavailable, and manganese and aluminum can reach toxic levels.
  • Bacterial nitrification and Fish metabolism (CO2) result in the formation of acids.

  –        Reduce buffering capacity of water.

  –        and lower the Ph.

  • Dissolved oxygen levels, nitrification, denitrification, carbon dioxide, fish waste, and the mineral content of the water affect and control pH.
  • Adjusting pH
  • • The pH in a recirculating system with relatively high fish stocking density (producing CO2), and adequate nitrification, will tend to decrease over time.
    • Low CO2 levels, excess plant growth (roots excrete alkaline compounds), anaerobic denitrification and mineralization of organic (fish) waste increases alkalinity (raises pH).
    • Add base chemicals (Potassium Hydroxide, Calcium Hydroxyde) to counter drops in pH, or (carefully) add acid chemicals (Phosphoric Acid) to counter a raise in pH.
    • Add limestone (hydrated lime), Potassium Carbonate, Potassium Bicarbonate or other common sources of carbonate (CO3--), to increase buffering capacity of water.
    • Do not add bicarbonate of soda to aquaponics systems, because it contains sodium which is toxic to the plants.

    what is your nitrates...I would think "0"

    I would think you do not have enough Fish waste (nitrates) to give your plants the nutrients they need.  if you add soluble seaweed extract to your system it will help your plants   till your fish get a bit bigger.  when I add a bit much worse thing that happens is I get a bit to much algae.  BUT my fish love ALGAE... on a side note that is why I added ducks to my system....helps cut down on the food bill

            ( I add soluble seaweed only when fish and plants ratio is off....I have room for about400 plants and about  500 fish...the stuff last a long time for me.

    It was recommended to me to start with green leafy plants until it gets established....that is  wait approximately 6months...before you add cucumbers or tomatoes to a new raft system ( a bit different for flood and drain). they called it till your system gets to a "sweet point"...this might be the reason your hydroponic system is doing so well....right now....but the aquaponic system will blow it out of the water soon.

    
    

[Jan R. McNeil]

I am sorry to say I am not to good at this blogging...so please do not be offended, if you already know this

I was looking at Reverse-Osmosis, I do not know much about it.

what I did find out seems more complicated then what I do, anyway

I found this, the Reply by Kobus Jooste.seem like he had your pH answers

http://aquaponicscommunity.com/forum/topics/reverse-osmosis

let me know how it works out, you got me wonding

[Keith Rowan]

i wouldn't mess with the ph, but do keep an eye on it.. when it drops (it will drop unless your media is affecting the ph) over time..

my first system took over 9 months, then suddenly dropped from the high 7's to the mid 6's.. and is now buffered to around 7.2 with shell grit