Chronic low PH in Fox Farm Happy Frog

I use Fox Farm Happy Frog and have chronically low PH in my runoff. Multiple plants, multiple grows across multiple times.

I have calibrated a higher end PH pen so I know thats not the issue. Soil is supposed to be 6.3. - 6.8.

Today is the first time I could water my new crop of plants to 10% runoff. The PH going in is 6.9 out is 5.6. Multiple plants all in the same soil (different pots of course). So why do all my plants have such low PH in the run-off? is FFHF not as PH balanced as they claim?


Every time I have had similar problems in Happy Frog it has been due to salt buildup about mid way through flowering. I perform a flush and the pH of the soil corrects back to ~6.5 immediately after the flush.


There are similar issues with the FFOF but if you do the flushes on the chart it seems to take care of itself.


Thanks for commenting. I’ve added no nutes. In fact I’ve had plants to start to finish in happy frog without nutes. Thoughts? I can flush them. Both ladies with low ph went into flower this week.

What is your water source???

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Not sure a flush is going to correct the issue and something else may be going on. Can you please tell us other things about your general grow environment (maybe other additives) in addition to the water source as Audiofreak has asked?

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Tap water at 7.5 ph. I use 2 drops of ph down per half gallon. This takes it to 6.9.

Aside from that I’m indoor, sf2000 light, no nutes have been added. No calmag added.
I’ve added lime today.

I’m stumped. Let see what @Myfriendis410 has to say.

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Sounds like the same as my tap water…any visible signs? Full plant pic may help those more experienced to notice something. This is the first time I’ve heard this issue with ffhf. @BobbyDigital may be able to help.

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Fox farms has been having bad batches (although they’ll never admit it). My suggestion would be to add lime but looks like you just did that. It takes time to work. How was it applied?

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Are your plants experiencing issues?

Now that I think about it, there have been a couple of people over the past 6 months or so that have had similar problems and this was called out.

I’ve been lucky since I always grow in FF HF and have never had the problem come up that wasn’t due to salt buildup.

Do your plants look ok?

Why chase numbers if your plants are doing well?

If you’ve used Fox Farms soils successfully over several grows why are you questioning it now?


My first thought. 5.6 is below nominal but still within soluble range for most nutes. As stated; FF recommends flushing salts at different intervals to correct just this issue. If not doing so you should be.

Two drops in solution to adjust means fairly soft water. This means that you will never be able to adjust the soil PH by running adjusted tap water.

I too have heard reports of low PH batches of FF.

Remember too that the PH will naturally drop throughout the grow. As organic material breaks down it acidifies the soil.

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Plants actually look good - so far. They are young.

@Myfriendis410 I amended with quarter cup of lime like you taught me last time. Anything else?

Just perform flushes at recommended intervals on the FF grow schedule.


I’ve been adding 6.5 pH water to my 2 plants. Runoff is between 5.8-6.2 pH every time. I been wondering as the plants seem ok.
Guess I got a bad batch of FF Frog.

IDK? I started again with FFHF. I watered for the first time today.
Water going in was at 65.5 Ph and came out at 53.6 for P1 and 52.2 for P2.

I have added lime this time. And some powdered Stump Tea to the soil and the Ph is coming out low.

Plants look good so I’m not going to worry yet. LOL

I just treat it right away with lime now or at the first major watering. One of the two. Good soil but I fight ph initially.