Seaweeds may drastically lower PH to dangerous levels?

[DavTom]

Hi,


Here is my story.

I found a reseller of Kelpak in The Netherlands, but after the first contact he went in silence mode.... So I have decided to start using a generic Seaweed brand that I bought some time go (I know that it is likely sub-optimal, but I assume that this is better than not using Seaweeds at all). It is written to use it at a concentration of 140ml/5 liters. To be really cautious, I started to use it today at 20ml/5L, so 1/7 of the recommended dose.

I have prepared a 5L of RO water with Rainmix fertilyser, which I well know that at the prescribed dose gives me a nice PH of 5.8. And indeed that is what I get when I measure the PH so I usually do not measure anymore the PH when I water the plants.

Today I have added 20ml of Seaweed and I do not know why...but I said myself, let's measure the PH just for curiosity...and...I could not believe it: PH 4.3. I calibrated the PH meter and...again PH 4.3. Then I measured other solutions of which I know the PH and the reading was as expected.

If it was just RO water with Seaweeds (i.e., without Rainmix), it does not need much acidity to drop significantly the PH, but there was already the Rainmix in the solution...
Well...I started to add my tap water to the 5L solution. My tap water has a high alkalinity (KH=10 German degrees and PH=8.4). It required me about 2 liters of tap water to get the PH to 5.8. This means that the acidity contained in the Seaweed is exceptionally strong. And I used it at just 1/7 of the recommended dose!

Question, did anybody experience something similar with Seaweeds?

Thx.

Dav