Test to lower Ph in RO wastewater and Tap

[GulfCoastDiscus]

Hello Water Experts.
I'm lowering the Ph on my waste water and Tap water. I place water in 5 gal bucket separately and added an airstone. I tested the Ph and tds.

RO waste water Tap Water
Ph-7.7 Ph-7.8
tds-630 tds- 510

I added 5 ml of Muriatic Acid in each bucket.
After 30min.
Ph- 7.1 Ph-7.4
Tds- 710 Tds- 580

In conclusion, although Ro wastewater have a higher Tds than the tap water the Ph fell lower in the RO wastewater than the Tap water. It must be because RO wastewater have lower buffering capacity than Tap water.

I'll test the water again after a couple of hours and see what happens.

Dan

I want to drop the Ph to 6.5

I tested again after 3 hrs. Ph went back up.

RO Tap
ph-8.4 ph-8.2

Added another 5 ml of acid.

I have made some test's on my water with M-Acid.
R/O and Tap as well as R/O mix with Tap.
I had reactions up to 48 hrs. In all cases I had a very low KH to start with, so the prb was dropping and stabilizing.

Am curios how yours end up.

Ronald

[Ardan]

Hi Dan,
What is the KH in both?

[GulfCoastDiscus]

Sorry Ardan. Don't have a KH test kit. I'm just winging it. I just want to know how much acid does it take to lower my Ph to 6.5
I'll pick one up tomorrow.

Dan

[GulfCoastDiscus]

From my last post I added another 5ml of acid. Making it a total of 10 ml. Tested the Ph after 4 hrs. and came up with

RO wastewater Tap water

Before acid is added
Ph-8.4 PH-8.2

Added 5 ml of acid
Ph- 4.0 Ph- 2.7

Why????
It just crashed.

I will need to start the test over and add less acid.

The result does not seem consistent. I thought the RO wastewater will have a lower Ph than the plain tap water.

I'll test the water again tomorrow and see if the buffer change anything.

Dan

[Carol_Roberts]

You don't have your waste water and product water lines reversed do you?

[daninthesand]

In the first addition of acid, neither the RO waste nor the tap dropped the pH much because both had some buffering capacity to buffer the small amount of acid you added. IE They both changed thier Ph by only about .5. Thius buffering happens rather quickly whcih is why you see the pH has not changed much after 30 minutes. Over time this ph is Higher (than it was without any muriatic acid) in both waters after 4 hours simply because the water has degassed (loss of CO2) which will increase the pH, long after the muriatic has reacted with the buffer.


The results you see on the last addition of muriatic make perfect sense. Your waste water has more buffering capacity (due to the increased concentration of solutes) so the acidity does not get as low, but still crasheds somewhat since you have actually exceeded the buffer capacity Whereas the tap has less solutes to buffer the pH, buffering capacity exceeded sooner ...hence the pH crashes even more than the RO waste.

Daniel

PS. Try adding the acid to RO water, then watch the ph crash!

I have used 7ml of acid for 30 gal.

The KH was at 1 DKH and the pH was at 9.4 out of tap.
After 24 hrs ageing the ph without acid was 8.4
With 7ml acid it droped to 6.3. But there was no buffer capacity left and it crashed to 3.5-4 in another 24-48 hrs.

Thought this might be of interest for your test's

Ronald

[GulfCoastDiscus]

No Carol. My lines are not reversed. Just trying to find a way to use my waste water. It comes out at ph 8.2 after aging and I would like to lower it. This is the reason for the test.
I just have to use less acid and see what happens from there.

Dan

[Carol_Roberts]

Are you trying to use the waste water to grow out discus? IF so I bet they would do just fine in the 8.2

[GulfCoastDiscus]

Hi Carol,
You're absolutely right but I like a lower ph. It's no problem anyway. I age 110gal overnight before it's use. I believe Discus evolved thousands of years at a lower ph and if given a choice they would probably prefer a lower ph.

Dan