PH:6 can't get it to move help needed

[telmor]

I have a PH:6 I have been dosing with PH Up for the past 4 days. The system is 1000 Ltr with 4 x 250 Ltr grow beds with clay beads.
I started dosing with 10mls of PH Up on the first day then I did 10mls twice the next day I followed this with 20 mls yesterday and again this morning. I have recorded no change in the readings.

Is there something else that I can do?

Regards

Maureen

[Yabbies4me]

What is the "pH Up"... is it Potassium Hydroxide?

Try adding lime to your system to get the system pH up in the short term. Dissolve a tablespoon of lime into a bucket of your system water, add to your GB 1/3 at time over three siphon cycles.

Add lumps of clean limestone or shell grit to your system for longer term pH control. Break some clean limestone into fist sized lumps and place them in your FT or ST, or mix a few handfuls of shell grit into your GB's.

From Murray on a recent thread:

Using Hydrated lime I mix two table spoons in a bucket of water then tip it into one of the grow beds and wash it in with another two or three buckets of water. That is in a system of around 1500 ltes or 450 gallons. That will bring the pH up from , say, 6.2 to 6.8 over a 24 hour period.

Cheers, Yabbies.
.

[Murray]

Hi Maureen,
Firstly, are you sure about your readings? Are you using test strips, if so they are very unreliable.
Get a Freshwater Test kit if you do not have one already.

Second, pH up is not all that good and too expensive.

SORRY, BRAIN SLIP THERE re HYDROCHLORIC ACID

[telmor]

Thanks for your responses to my question. We have had about 60mls of rain in the past weeks and our rainwater has a PH:6 so I shall have to dose my top up tanks to raise that PH.
The PH Up that I am using is Science Prods. brand and contains Sodium Hydroxide 4.8% W/W (whatever that means).
I am a little confused by your reply Murray suggesting the use of Hydrochloric Acid, I used that last year to reduce the PH when I had a reading of PH: 7.8 - 8.0. It seems like adding acid to acid, or am I missing something?

[Murray]

No, it is me. Trying to answer posts while on the phone with someone else......sorry.

[RupertofOZ]

Use some "hydrated lime"... rather than Sodium Hydroxide.... otherwise known as Caustic Soda... and even... "Draino"...

[Gratilla]

Just because Sodium Hydroxide is STRONG (and reputedly used by the Mob for disposing of inconvenient bodies) doesn't mean it shouldn't be considered. In fact, I think its preferable to Calcium Hydroxide. Here's why:

2) It's strong, so only a small amount is needed (and its impact on sodium levels is minimal). If buying it in its crystal form then dissolve it first, but be careful as it gives off a lot of heat when dissolved.
1) It's highly soluble (whereas Calcium Hydroxide is only sparingly so) thus its effect on pH will be immediate. With Calcium Hydroxide only that part which has dissolved (and is in its ionic form) will contribute to pH. The undissolved balance will only affect pH as it slowly dissolves (over days), so you may be tempted to add more and overshoot pH-wise.

[RupertofOZ]

Just because Sodium Hydroxide is STRONG (and reputedly used by the Mob for disposing of inconvenient bodies) doesn't mean it shouldn't be considered.

It's not a lot stronger than Calcium, or even Potassium Hydroxide.... it's the hydroxide base that buffers the pH..

However there are good reasons... for not loading your system with Sodium... including the fact that Sodium has minimal benefits for plants ... in comparison to Calcium, and particularly Potassium...

In fact, I think its preferable to Calcium Hydroxide. Here's why:

2) It's strong, so only a small amount is needed (and its impact on sodium levels is minimal). If buying it in its crystal form then dissolve it first, but be careful as it gives off a lot of heat when dissolved.

I disagree completely with regard to it's "impact".... and the heat reaction is a very good reason... not to use it...

1) It's highly soluble (whereas Calcium Hydroxide is only sparingly so) thus its effect on pH will be immediate. With Calcium Hydroxide only that part which has dissolved (and is in its ionic form) will contribute to pH. The undissolved balance will only affect pH as it slowly dissolves (over days), so you may be tempted to add more and overshoot pH-wise.

Again, I don't belive this to be true... and any residual "undissolved" buffer is not only minimal.. but beneficial....

There should be no need to buffer pH every second or third day anyway...

Calcium Hydroxide... or "hydrated lime" as it's commonly known as... is readily available... and cheap....

It is an entirely suitable buffer... and provides needed Calcium for the plants...

Personally... I would recommend alternating between a Calcium & Potassium buffer....

But I would not recommend a Sodium buffer.... and while Sodium Bicarbonate... baking soda... is sometimes used in RAS as a pH buffer... Sodium Hydroxide.. is not...

And even baking soda is generally not used, unless it's all that is to hand... or because it's cheap....

Frankly the argument for using baking soda... because it's "Cheap"... is a furphy IMO... as hydrated lime is cheap as chips...

[Murray]

It is a long established practice to buffer with Hydrated lime as it delivers a double benefit namely , buffering and adding calcium to the system.

Alternately a potassium based buffer is used for the same two reasons, to buffer and to add potassium.

Potassium is often overlooked in AP with the outcome of non setting flowering plants and no or poor yields particularly with tomatoes.

Three elements do not come into an AP system readily and they are calcium, potassium and iron. So by using the two products to buffer the system we also add two plant necessities.

Chelated Iron is added as a separate process.

[Gratilla]

[Sodium Hydroxide] is not a lot stronger than Calcium, or even Potassium Hydroxide...

Molar/Normal Sodium Hydroxide comes in at a pH of 14 (ie it dissociates completely). Saturated Calcium Hydroxide has a pH of 12.4 (I checked), so getting on for 100 times more of the latter would be required to have the same effect on pH as the former (logarithmic scales remember?)

If you truly believe that "[Sodium Hydroxide] is not a lot stronger than Calcium [Hydroxide]", I challenge you to stick your hand in a Normal (or stronger) solution of the former for an hour or so and report back.

I disagree completely with regard to it's "impact".... and the heat reaction is a very good reason... not to use it...

1) Read the above re relative pH's and logarithmic scale etc.
2) "The heat reaction is a very good reason" to make a dilute solution beforehand as I (and Yabbies) mentioned above.

Again, I don't believe this to be true...

Which part? I make five statements in what you quoted; each of which I stand by.

If you (re)read Maureens's OP, you'll see that it relates to rectifying a low pH and the most effective way of doing this would be Sodium Hydroxide. Calcium, Potassium and Buffering may well be of interest, but not directly relevant.

BTW, could tell us at what pH Slaked Lime buffers?