Help Please on PH

[Kyle Minter]

I have a 4500 gallon, 3 year old koi pond. This year we decided to turn in some aquaponics system. My toms, squash, cukes, peppers, and melons were planted on the weekend prior to Easter. We installed a 275 gallon ibc tote for a multi layer sand filter, pumped by a 70 gpm pump. The system that i have decided is a constant flood trickle system to fill my 5 gallon (homemade bato) buckets filled with part river rock on bottom, toped with a 33/67 mix of perlite/expanded shale. I have read a lot about new systems in that a high ph is quit common, however I thought an experienced pond would make the transition to AP system much more easily. It has been over a month now and my ph is still at 8.5+, ammonia, nitrite, and nitate are all at 0. we are feeding regularly. I am really trying to not add anything to lower the ph because i know it will go down in time. But the results are not pleaseing as of right now for me. my plants have badly yellowing lower leaves along with purpleing. along with a not so average growth rate of stem and leaves. I am extremely concerned with the progress right now. i have put quit a bit of funds in this and would absolutly love some better results. PLEASE help, i am very concerned!

[Jonathan Kadish NYC AA Chair]

You will probably need to supply your pond with rain water instead of well water. What is your ph out of your well?

[George]

Gradually lowering your PH with PH DOWN FOR HYDROPONICS would be an option and another expense.  In the water section of the forum there are discussions on PH.  My system has been hovering at around neutral for 4 months and I'm feeding every day.  It is nitrification which naturally lowers PH so I'd feed the fish.  Good luck.  I don't think you should be too concerned this early.  Your water quality is good (other than high PH) so just keep an eye on that.

[Kyle Minter]

i live in the country so its "city" water i guess and the ph in it is at like 8.5. the problem with the rain water is that we have to top of the 4500 gallon pond every other day which adds up to a lot of water. and since i live in north Texas rain water is not in a large abumdance. will the PH Down for hydro be safe for Koi? and will it cause the ph to go up and down causeing stress on the fish? Thank you for your help again?

[Nate Storey]

Do not use pH down in your system.  pH down for hydroponics is not always safe for fish and will not fix your problem. You most likely have a carbonate issue- and the only way to deal with it is to: install an RO filter and top off with that (you'll still have to wait for your pH to drop), or empty your pond, remove all of the sediment and carbonate rocks and start with RO water (what I would recommend).  

Carbonates are your worst enemy.  Save yourself some money in the long run, invest in an RO filter, and start from scratch on your tank.

[TCLynx]

Nate is probably right.

There are some Acids that you can use to lower pH, however, you should not do it in a system with fish.  I normally recommend a separate tank to prep your top up water and let it stabilize before using it in the system.  However, doing this constantly to top up a large system when you live in a location where the well water (or city water) is hard and you can't collect enough rain water to make a dent in your needs is not really a good option.

Nate Has experience in large scale aquaponics in a location with hard water and not enough rain and he grows some beautiful plants.