PH at 8.4 why ????

[gprovo]

It has been a while since I checked the PH in my planted tank but recently replaced a bunch of Amazon broadleafs and did some testing also.
I have a 125 planted (Amazons and Crypts) that has been set up for about 3 years. I have PC lights 4 96 watt 10K and 1 96 watt Actinic. I also use CO2. Filter is a wet/dry with sump. and 3 light power heads for water movement.
Water changes about 25% every 4 weeks. Bio load light with 5 angels and 5 botia, and lots of Malaysian trumpet snails. No die offs of any type. Did have some slime algae problems a while back but seems to be under control now.

My well water is ph 7.4 and mu topp off RO water is also 7.4
Phostphate 1.0 and Nitrate 0
Temp about 75
Fertilize about every 3 months with fertilizer sticks.
Substrate about 3-4 inches of Red River Pebbles.

So the question is what would cause my PH to go to 8.4?
Any advise would be appreciated.
Thanks

 

[QTOFFER]

Welcome to AA, gprovo!!!

I would check your CO2 system, especially the diffuser. Is it injecting less than you think it is?

What is your kH (carbonate hardness)? If you have well water, I would suspect that it is considerably high. High kH drives pH upward, but this is negated by the addition of CO2, which produces carbonic acid when dissolved in water. If your CO2 system is putting less CO2 into the water, the pH will be able to creep upward.

 

[Jchillin]

You have fish in this tank? A rise in ph of that magnitude would have some negative results on your livestock. How are they doing?

 

[gprovo]

I have 5 large angels and 5 botia's that have been in the tank about 4 years and seem well and are spawning.
Just checked my KH and it is high at 286 in the tank and 250 KH at the source.
Phosphates are at 0.

I will start up the CO2 again and do a 50% water change.

 

[gprovo]

AAAAAAGH Ph stil 8.0

Did a 50% water change using well water at 7.4 ph.
Tank dropped to 7.6 - 7.8 ph.
48 hrs later water was back at 8.0 ph.
Started using co2 again ( slow bubble count approx 50 a minute)
PH still at 8.0.
Cannot figure out what is causing PH to stay this high?????????

Please advise......

PS: Angels fish laying eggs on new Amazons leafs.
Small Amazon (different varieties) leaves are starting to look bad and blue green algae starting to show up again.

 

[NoSvOrAx]

16 degrees of kh with a ph of 7.4? Something else is in your well water. It would take 20ppm of co2 to bring that water down to 7.4. Odds are you have something in your well water that is escaping after you add it to your tank, like co2, and the water is rising to its normal ph. I'd do a co2 test on your well water. If its not co2 then you have some other acidic compound in your water that is disapating.

 

[gprovo]

My well and house are located in the middle of a corn and soy bean field.
At this time of the year the fields are being fertilized, tilled and Anhydrous Ammonia is also being added. Even though my well is about 45 feet deep I wonder if this could be a factor. Still the well water is coming out at 7.4 Ph.
I am wondering if my substrate could be causing this problem. It is called Red River Pebbles at least by the LFS. It is about 5 years old. Is there a way I can test the pebbles?

Thanks for all your help.
Gil

 

[An t-iasg]

Here is how I would test the pebbles: Get a cup/bowl (whatever a handful of pebbles will fit in) of your well water and test its KH and pH. You already know this, but test anyway after you fill the cup/bowl. Add the pebbles and let that sit for at least 24 hours. Test the water that the pebbles are in again. You could let it sit for a few days and repeat the test.

After 5 years, you would think that any minerals that the pebbles may be dissolving into your water would be a little lessened by now, but maybe not. For example, my Eco Complete substrate buffered my KH up to 6 degrees. My tap KH is 3 degrees. After about 6 months, my tank KH matches my tap KH again.

 

[gprovo]

Good idea, will try.

Thanks for all your help.

 

[An t-iasg]

You're welcome

As an added test, you could pour another cup of your tap/well water and let it sit out (just the water, no pebbles) and test it in 24-48 hours, if you haven't done this already.

 

[gprovo]

AAAAAGH...... still 8.4 ph plants are all looking terrible.

It is now Nov 30 and the results are:
Tank water is at 8.4 ph ( water change 50% 11/19 & removed drift wood)

Tap water 11/17 ph 7.6 standing till 11/30 ph now 8.4
Tap water w/pebbles now ph 8.4
Tap water 11/30 fresh is at 7.4 ph
TDS tap fresh 477, standing tap 641, tank 672

Also contacted Red Flint gravel (where my substrate came from) and also the LFS that sold it to me and who also uses it in his tanks - dissolving issues is less than .01% acidity -

Any ideas would be appreciated.

 

[rkilling1]

The pH sounds just right to me. If your tap water turns out to be 8.4 after sitting out, then I don't see a problem.

MANY plants live and thrive in hard water. I can only think of a few that NEED soft water inorder to thrive.

Having a tank with a pH of 8.4 and driving in down to 7.4 with CO2, sounds just about right in my mind.

I think you are hunting down the wrong issue here.

How old are your light bulbs?

What are you dosing now?

Do you have a CO2 drop checker?

What is your BPS (bubbles per second) of the CO2 being injected?

What are the parameters of your aquarium?

NH3
NO2
NO3
PO4
KH
GH
Temp
Filtration
Type of CO2 injection
Ect...

It sounds as if you aren't injecting nearly enough CO2. Having a wet/dry sump doesn't help this out AT ALL. It will off gas a lot of the CO2, so you need to be vigilant in maintaining 30 PPM CO2.