PH Crash Confusion

50g Planted Freshwater.
15 months old
1x Pearl Gourami
1x Angelfish
8x Red Eye Tetra
5x Oto
3x Rummynose Tetra

I did my usual 70% Weekly water change yesterday.

My PH dropped to 5.6

This morning when the C02 kicked in it quickly dropped to 4.8

I have turned the C02 off.

Normally I have 6.8PH dropping to 5.8PH with CO2.

I recalibrated my PH probe. It's perfect.

Put the probe in a cup of tap water 5.6PH

Put the probe in a cup of mineral water 7PH

Seems my utility is suddenly giving me tap water of 5.6 where previously it's always been 6.8.

If I leave the C02 off I guess I can hold the PH up to 5.6, but my plants will suffer a lack of C02.

If I continue to inject CO2 then my PH will drop to 4.6 - this scares me.

What do you think I should do?

 

I've put a couple of small bags of crushed coral in the tank near the output flow, as an intermediary measure.







Still hoping for suggestions

 

Hi everyone. A little bump for this. Anyone?

 

Seems like your water supply had a change.

Do you know your tap water kH?

Tank water kH?

 

Seems like your water supply had a change.

Do you know your tap water kH?

Tank water kH?

Hi Chanyi,

My tap water has previously always been, 6.8PH, 0KH, 2GH.

My tank has always been 6.8PH (dropping to 5.8PH with CO2), 1KH, 2GH.

I've posted in the past that I don't know why my PH is so stable with such low KH, but the tank had never had any PH drop.

I've been able to get the PH in the tank back up to 6.5 using crushed coral.

I'll need to check the tap PH on Saturday prior to my next water change.

But what should I do if the tap continues to come out at 5.6 PH?

 

Hi Chanyi,


But what should I do if the tap continues to come out at 5.6 PH?

Dose 0.5 degrees of kH using KHCO3 into your new water change water.

Or you can go with RO water and blend up anything you want.

Do you know the TDS of your tapwater?

 

Dose 0.5 degrees of kH using KHCO3 into your new water change water.

Or you can go with RO water and blend up anything you want.

Do you know the TDS of your tapwater?

OK. How much potassium bicarbonate per gallon would you add to increase the PH by 1PH?

I picked all my fish based on my tap water so I wouldn't have to play with water chemistry and now the tap water has changed.

 

OK. How much potassium bicarbonate per gallon would you add to increase the PH by 1PH?

I picked all my fish based on my tap water so I wouldn't have to play with water chemistry and now the tap water has changed.

0.068 grams per 1 US gallon KHCO3 will raise kH by 0.5 degrees. This will also raise pH.

You will be changing mineral contents and osmotic pressure by doing this, so you should do it slowly to avoid shock to livestock.

You also want to mix up a big batch for a water change, don't change the water and then dump KHCO3 into the tank, that will cause kH and pH swings while it balances out.

Do you know the TDS of your tapwater?

 

0.068 grams per 1 US gallon KHCO3 will raise kH by 0.5 degrees. This will also raise pH.

You will be changing mineral contents and osmotic pressure by doing this, so you should do it slowly to avoid shock to livestock.

You also want to mix up a big batch for a water change, don't change the water and then dump KHCO3 into the tank, that will cause kH and pH swings while it balances out.

Do you know the TDS of your tapwater?

OK. Thanks for the advice.

The TDS in my tank the only time I tested it was around 180.

I lost the TDS pen and never got around to replacing it.

I've never tested the TDS of the tap, but presumably it would have been at 180 or under.

 

This was my tank on Saturday when I noticed the water change had dropped my PH from 6.8 to 5.6.




Four days later the crushed coral bags have brought my PH back up to 6.9.

But my plants have been wiped out.




It looks like the grass is dying from the roots up.

Every morning I'm finding 20+ long green stems floating at the top of the water, as the base of the grass is turning translucent yellow and dying.

Not sure if this was the PH crash or something else the utility put in the water at the same time.

Unfortunately I've also lost three of my Oto's since Saturday - I'm sure it was the PH swings that got them.

 

You're going to have to look into your water source report to figure out what they are treating the water with.

 

Ok. Now I'm really stumped.

My tap water returned to the usual 6.8PH, but my plants were already beyond saving.

I've turned off my CO2 injection until I can work out what's going on with my PH, and because I have no plants.

I did an 70% water change on Sunday. PH6.8

On Monday morning my PH was 6.2 - I added a couple of bags of crushed coral to the tank, by 9pm I had PH6.7.

I tested my tap water again - 6.8PH.

I removed all the dead plant residue, ran my hands through the gravel and removed the old roots.
I vacuumed 100% of the gravel.




Monday night I did a 80% water change. PH6.7.

Woke up this morning - 10 hours later - PH6.0 !!!!!

Ammonia 0, Nitrite 0, Nitrate 0-5ppm.

..but what does this all mean?

Why the continued PH drop?

Old Tank Syndrome - The tank is 15 months old. The cycle has been rock solid during this time. Yes, when the plants died I would have expected some ammonia to be produced, but I didn't actively measure any at any time (my bad) or see any signs of it. The substrate is pretty clean and clear of organic waste right now. Their is nothing else in the tank. OTS seems unlikely.

Cycle Crash - Again I would expect a rise in ammonia. If the cycle had crash that ammonia would not be turned to Nitrite and Nitrates, so I would expect the PH to stay stable or go up (ammonia is an alkaline). So, why would the PH drop.

As for my Ammonia, Nitrite and Nitrate readings from today - there are as expected considering two large water changes within 48hrs - and the Prime could be masking some of these readings?

I'm lost.

My replacement plants have arrived! I really don't feel ready for them, or to turn the CO2 back on, or to start adding fertilizers, but I guess I have no choice.

Guess I'll replant, add ferts, switch the CO2 back on.

I think I'll add some stability as well - but I don't feel like I know what I'm doing - Help!!!

 

OK.

I've replanted.




I've turned the lights back up to a plant growing setting.
I've buried 8 root tabs.
I've added EI dosage for KNO3 and KH2PO4 (I'll add CSM+B and Iron tomorrow)
Oh, and I added some Stability, just for luck.

.. but I can't bring myself to switch the CO2 back on with a PH of 6.1.

Hopefully the crushed coral bags I reintroduced this morning will have my PH back up to 6.5-6.8 by tomorrow morning, in which case I will start up the CO2 in the morning.

Still feel like I need to get to the route cause of this issue.

Let's see if the plants make it through this week.

 

You need to test degassed tapwater pH and kH, degassed tank water pH and kH

You previously stated tapwater kH of 0 meaning you have 0 buffering ability, and thus your pH is dropping slightly to 6.0 from humic / biologically produced acids via the cycle.

Begin dosing 0.5 degrees of kH from using KHCO3 into new, incoming water.

Start with a 25% water change, and mix up a batch of new water @ 0.5 degrees of kH.

Then do a 50% water change a few days later following the same steps --> Mix up a batch of 0.5 degrees kH tapwater.

Then proceed with 50% or larger weekly water changes all with pre-mixed up water, dosed to achieve 0.5 degrees of kH.

 

You need to test degassed tapwater pH and kH, degassed tank water pH and kH

You previously stated tapwater kH of 0 meaning you have 0 buffering ability, and thus your pH is dropping slightly to 6.0 from humic / biologically produced acids via the cycle.

Begin dosing 0.5 degrees of kH from using KHCO3 into new, incoming water.

Start with a 25% water change, and mix up a batch of new water @ 0.5 degrees of kH.

Then do a 50% water change a few days later following the same steps --> Mix up a batch of 0.5 degrees kH tapwater.

Then proceed with 50% or larger weekly water changes all with pre-mixed up water, dosed to achieve 0.5 degrees of kH.

Thank you Chanyi - I appreciate your help.

My KH, both tap and tank have always been too low to read, but for some reason my PH has until now been very stable.

Perhaps it was the relatively high Nitrate (40ppm) and some magnesium (Epsom Salts) in my tank having an alkaline affect that mitigated the low KH.

I don't know really. I suspect while my KH has always been very low (off the scale) the utility is now giving me water that is even less buffered than before.

I was really hoping to avoid additives for PH/KH as I hate the idea of chasing these numbers, but at this point I think you are right.

I'll probably start adding a little baking soda to each water change.

I'll avoid KHCO3 as I'm already adding KH2PO4 as a fertiliser and don't want to have to recalculate due to KHCO3, and then have my ferts tired into my KH buffer.