Return to the Hydroponics Forum | Post a Follow-Up

adding nutes lowers PH WHY?

Posted by tabbycat123 6 (My Page) on
Mon, Mar 24, 08 at 19:30

We have an issue with starting a new drip system ... the PH of our tap water is 6.5 ,once the nutients are added we go right off the chart to a whopping 4 ??? We added 2 teaspons of Fox Farm Grow Big to a gallon of tap water (the res holds one gallon)... Please help, what do we need to do to correct this? HELP :)

Follow-Up Postings:

RE: adding nutes lowers PH WHY?

I think it is the nature of nutrient solutions to be acidic. they'll just about always lower your pH, though admittedly, 2.5 points seems like a lot.
I'm not familiar with fox grow, but 2tsp per gallons seems like a lot.

RE: adding nutes lowers PH WHY?

Your tap water is acidic? That's unusual, and - so I've heard - illegal in some countries (corrosion, etc).
Sure that's correct?

RE: adding nutes lowers PH WHY?

Probably well water. Add baking soda in TINY amounts. Like 1/8th tsp, then stir, wait a minute, re-stir and retest. The less you use to get your solution in the 5-6.5 range, the better. Sodium (from baking soda) is not particularly good for plants.

The nutrients are pretty acidic. I see a 2 pH drop from 7 to 5 when I put 2500 ppm of the Flora fertilizer in water (which is substantially more than the recipe on the bottle calls for). It doesn't seem to affect the plants, but 4 probably would.

You could also use lime (CaO). As opposed to baking soda, it would probably be a benefit to your plants since it's free calcium, but I tried it twice and ended up with pH 8.5+. You might have a more steadfast hand though.

RE: adding nutes lowers PH WHY?

if you don't have a steady hand, you could mix a dilute lime mixture. Say 1 cup in 1 gallon. then when you add 1 cup of this mixture, it'd be the same as 1/16 of a cup or 1 Tablespoon.
Just a thought for more control.

RE: adding nutes lowers PH WHY?

thank you for all your help.

i have been using baking soda to bring it back up. used about a 1/4 tsp for 8 gallons to get the ph back up.

what is this lime (CaO) mixture you are talking about? sorry, im a newbie, but trying to learn. sounds like id be better off using that since its good for the plants. thanks!

RE: adding nutes lowers PH WHY?

lime is that white stuff they use to line school football fields. It's high pH, and being made of only calcium and oxygen, quite good for plants. Tricky to use, but grizz's suggestion above is brilliant.

Lime is sold at any garden store, but maybe only in 50 lb sacks. We have low calcium soil here in La, so we go through a bag every year or two. If you have no need for it in your lawn or garden, it'd probably be difficult to justify buying/storing a 50lb sack of it.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Hydroponics Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here