Gh, Kh, Ph help (please!)

[Pond*Mom]

Some hand-holding needed here, please.

I have read the thread on PH, but I guess I just need someone to walk me through this.  My (city) source water has changed in the last year and my pond's #'s don't look right to me.  Last year, I had a steady Ph of 8.6; gh of 150 and kh of 300.

Today, PH 9; gh 60; kh 330, I did do a partial water change yesterday, but those readings have been consistent.  Like many, we've had more than our share of rain.

Source water is PH 7.5; gh 60; kh 210.

Just how close to disaster am I? I believe I need to raise the gh and lower the kh.  To raise the gh, I use Epsom salts (right ?) I am not sure what I use to lower the Kh.

My pond is a year old, 513 galloons, 3000 gph pump to 15' stream, three drops into pond; two-stone aerator.  Had a "professional" spring clean-out. Pond contains two 10" koi and a few assorted goldies.  I do regular water changes (weekly or biweekly depending upon weather). Never had a problem with nitrites or ammonia, which I suppose is good given my high ph.  The only change I can think of, is that I switched over one bag of lava rock this year to bioballs.

I'm concerned about my O2 levels, but have lost the instructions to my Tetra O2 test kit (anyone have them?)

My fish appear to be happy and eating well.

So, is there anyone out there who will walk me through this?

 

[MCA]

Koi are best served by stable, relatively soft water.    But they can survive in a wide range of conditions.

Your source water readings appear to be just fine.   

Rain water will not bring in minerals to contribute to higher KH or GH.  Typically rain water brings in carbon dioxide as carbonic acid.  So after a rain, if the pH moves, it should be downward.  But, it shoud not move from a single rain (barring a hurricane amount),   If it does, there was probably too low KH (such as under 200).   

The interesting question is why is your pond kh level higher than the supply water?  Do you have exposed concrete (such as blocks holding up plants), lime plaster, or limestone or coral in the water column?   ....or have you been adding baking soda?    Must be something like that.

Here in Hot 'Lanta we have very soft water.   The pH stays around 7.2 (could not ask for better) and the gh and kh are both 100mg/l or less.   

By the way.....ammonia is MORE toxic at higher ph....not less.    That is why if you have had koi in a bag for many hours (such as being shipped in from Japan), you do NOT want to open the bag, leave the fish in that water (full of ammonia) and let the ph climb as the carbon dioxide is exhanged with O2.  You want the fish out of that water as soon as you open the bag.

You want DO levels at 80% of saturation.  But the warmer the water the lower DO saturation becomes.   Cold water carries more DO.   A good safe rule is already have at least 8mg/l of DO.

Did any of that help?

[RickF]

With source water like yours, I would not do anything but regular water changes.  Stability is more important than anything else.  With a KH of the source water at 210, you will be fighting a constant uphill battle to move the pH from where it wants to be, but there is no reason to try to move the pH.

It is true that Epsom salts will raise the GH, but Epsom salts adds only Mg++.  If you are using baking soda to maintain KH, then you need Ca++ (which can be added as calcium chloride) to prevent the baking soda from taking the pH above 8.3.  In places with no naturally occurring GH, the usual practice is to add equal amounts of Epsom salts and calcium chloride.

In your case, I would not add anything.  Your source water is fine, and regular water changes should keep the pH stable.  Where I live, the source water has 0 GH and 0 KH out of the tap.  In that situation, the pH will fluccuate all over the place, so short of having a constant flow-through system (which with our manditory water restrictions would not be possible), I am forced to add baking soda to raise the KH and calcium chloride to raise the GH.  I raise the GH, not because a high GH is better, but because without the Ca++, baking soda is an incomplete buffer.

[Roddy Conrad]

If you increase the GH with calcium chloride flake to last year's GH levels, the pH will automatically and gradually adjust to match last year's lower pH values, since higher calcium content lowers the pH automatically from those pH 9 values in most situations.

Others above advise leaving it alone, and they are correct in that the readings are not normally a significant problem at the current values.  I prefer the slightly lower pH you will get if you bump the GH up to the 100 to 200 ppm range by adding a pound of calcium chloride flake per 1000 gallons of pond water.  But you CAN just leave alone as others advise above, no argument with them.

[Pond*Mom]

First, I don't think there's anything in pond that should raise the Kh. Just river rock and gravel.  I am not sure what type of rock is used for the waterfall ledges ... it has an almost "fools gold" metallic shine to it.  I guess I could ask the installer.  And I've never added baking soda.  So the difference is a mystery to me.

So, the lower gh isn't a problem?  Okay, then I won't do anything.

  BUT if I wanted to lower the gh (& ph) somewhat, I would add the epsom salts and calcium chloride.  Wouldn't I have better luck with my plants if the ph was somewhat lower?  I hope I don't sound stupid, but where would I get calcium chloride? 

[Lotusman]

Pond*Mom,
I found calcium chloride at the pool supply store. Kind of expensive in a small 4lb tub. Maybe you will get a better deal.

[RickF]

  BUT if I wanted to lower the gh (& ph) somewhat, I would add the epsom salts and calcium chloride.  Wouldn't I have better luck with my plants if the ph was somewhat lower?  I hope I don't sound stupid, but where would I get calcium chloride? 

Adding Epsom salts and calcium chloride will RAISE the GH, not lower it.  Epsom salts will do nothing to the pH, but it will raise the GH.  Calcium chloride MIGHT lower the pH, but it all depends on what is causing the KH.  If you did not add baking soda (and since your source water has a high KH to begin with, there would be no reason for you to have done so), then we do not know what is contributing to the KH.  f it is Carbonate/bicarbonate, then adding calcium chloride will bring the pH down to 8.3; however, if it is phosphate or any other naturally occurring buffer (other than carbonate or bicarbonate), then  calcium chloride might not have any effect on pH, either.

Whether you will have better luck with the plants at a lower pH depends on what plants you have.

A less expensive source of calcium chloride, but unfortunately only available during the winter and in places that actually have winter - I rarely find it in North Carolina, is the large bags of ice removal flakes.  Read the label carefully, though.  Some ice removal products are rock salt (sodium chloride), some are a mixture of urea and potassium chloride, and some are calcium chloride.  Only buy the one that is calcium chloride.

[Pond*Mom]

Sorry, I meant to raise gh.

I have some ice melt in the garage, I'll check to see what it is.