Raising KH & GH and lowering PH

[campingcreecher]

I test my pond water twice weekly and do a 10% water change weekly. We have been experiencing an algae bloom for 3 weeks now. I would really love to get rid of the pea green water so I could enjoy my pond more. I am worried about the high ph reading I get in the evening. Here's what I test and what they read.

am - 0
nitrite - 0
nitrate- 0
phos. - 0
ph (am reading) - 7.5 (evening reading) - 9.0
KH - 71.6
GH - 71.6

We turn the aerator off during the day and on at night. Thinking that might help with the algae bloom. I have read that adding Baking Soda will raise the KH. I'm afraid that will raise my ph too. I sure don't want to raise the ph anymore. I've noticed my water hyacinths look stresses and my lily's too. Fish look happy and hungry as always. Though, I did notice on one of my fancy fin koi's, that her tail fins looked a little frayed. My pond is 2600 gal. We have a bottom drain that goes to a 275 gal. settlement chamber, then into 2 different bio filters, then up to 2 more sand and gravel filters both 55 gal. each.

Any help on safely raising the KH & GH and lowering the ph and algae would be appreciated. I have not put any salt in my pond. I know some do and some don't.

 

[HTH]

How long has the pond been up and was there any event just prior to the water going green.

 

[campingcreecher]

We have had it going since November of 2012. Its a rebuild previous pond was too small so we increased the size. We have a waterfall then flows down a stream into a small pool maybe 8 ft diameter and 15 inches deep with lots of plants and a small bio filter that also feeds into this pool. Then all water goes over a spillway into the big pond. We have had more rain than I can ever remember, over the past 3 weeks. Not sure if the rain would have anything to do with it?

 

[crsublette]

The pea green water algae is likely the primary variable causing the pH fluctuations. During the day, the algae is consuming carbon dioxide and other inorganic carbons causing the pH to increase to be higher by evening time. During the night, the algae produces carbon dioxide causing the pH to decrease to be lower by morning time.

Two approaches to clear up pea green water: 1) using a properly installed UV device (very fast solution); 2) quilt batting in trays (which works, although a bit slower) and another thread talking about its effectiveness of removing it.

Rain can also have an impact on KH consumption and lowering your pH.

Also, check out these threads.

Proper KH and GH levels - Since you want to keep your pH at this level due to the concern of your plants, then be careful how much you raise the KH. At this KH level, depending on how you manage the pond, there is a risk of this low KH allowing the pH to fluctuate on the low end of the pH scale. KH only stabilizes the low end pH fluctuations.

Calcium chloride to lower pH - This will only lower it to around the mid-to-low 8s in pH. This increases the calcium concentration. Calcium only stabilizes the high end of the pH fluctuations.

How to stabilise pH at 7.0? - I do not recommend you lowering your pH. It is a tricky game to play to lower the pH in the context of our outdoor ponds.

What kind of salt? and is salt healthy for a pond? - Salting ponds is an old school treatment that is now mainly used in quarantine situations.

Algal Blooms - For more general information about algae.

 

[campingcreecher]

I tested this morning, the PH was 7.0 and the KH and GH were still 71.6. The other tests listed above were 0. Should I go chasing the KH and GH by using baking soda?
We do have a UV connected into the system. Its only a 9 watt for a 1800 gal. We had it hooked in to the pond before the rebuild. Your right, it did an amazing job keeping the water clear as a mountain stream.

 

[crsublette]

If the problem we're talking about is pea green water, then a 9 watt UV for a 1800gph flow may likely be failing you due to the fact the UV bulb loses its light spectrum strength over the hours of use or the light spectrum from the UV bulb is simply not strong enough. To resolve this, place the UV on a bypass flow, place a valve prior to the UV on the bypass flow, place a valve on the main flow, properly control the main flow valve and bypass flow valve to slow the flow rate through the UV, and this will slow the flow rate to better match the UV bulb's strength. However, there's a point where the UV bulb simply will need to be replaced.

Yeah, if your pH is 7 in the morning and 9 in the evening, then I would definitely look into controling the algae problem as soon as possible. Once algae is resolved and the pH is still fluctuating this bad, then you will need to fix it by properly adjusting the KH value, as explained in the prior hyperlink shared, titled "proper KH levels". For beginners, the only reason to chase the GH value is to make sure the calcium concentrations are at a proper level and the proper level is different for everyone's pond due to their water chemistry.

 

[campingcreecher]

I'll check the ph again this evening. I know we have adjusted the flow through the UV; and the bulb was new when we turned it on in May. The replacement bulbs I purchased were off Ebay and not very expensive for a pack of two. I didn't think they seemed as bright as the bulb that came with the unit. Maybe I'll order some more replacement bulbs. Do you have a recommendation of a trusted seller that carry's quality replacement bulbs? Thanks for your time!

 

[crsublette]

Yeah, Ebay is a tough one. As you probably know, not all sellers are reputable there. I only buy material on ebay that I know the quality can be easily judged by the picture or if I am referenced to a particular seller.

Also, the UV lamp makes a big difference as well. Sometimes the lamp might need to be replaced. This is the problem with cheap UV devices since the lamps are usually not built too well.

I don't know what type of UV bulb your UV lamp requires, but, here are some trusted sellers on UV bulb replacements...

Atlanta Light Bulbs - Germicidal Bulbs - UV

1000bulbs.com

Koi Pond Central (only sells particular brands)

Quality UV Lamps

Arizona Ponds (only sells particular brands)

 

[campingcreecher]

I have purchased from Atlanta Light Bulbs before. Think I will order another bulb from them. I'll retest the ph this evening to see what the swing is. Thanks for your time and help.

 

[crsublette]

Hey no problem at all. :banana: Hope everything gets straightened out. Everything here should get ya straightened out, but give a yell anytime if ya need some clarification or a question. :claphands:

 

[campingcreecher]

Hey Charles,

I tested the PH. Bad news, it was a 9.0. Yikes! Big swing from 7.0 this morning. I rinsed out all filters added in a large amount of quilt batting into the filter in the settlement chamber. Also mixed up some Aqua Gold from fish pharmacy to help break down the algae. Turn off the UV at least for the next 24 hrs since I put the Aqua Gold in (directions recommend turning off UV). I have a scheduled water change for Thursday. What else should I do to get the ph down or should I even worry about it? My KH and GH are still 71.6, Ammonia is 0, Nitrites 0, Nitrates 0,. Sorry to bother you so much.

 

[crsublette]

Yikes, yes, that is an unhealthy pH swing.

Added a post (#10) on the calcium chloride thread that might help clarify the issue.

Due to the presence of algae and without sacrificing the health of the fish, the lowest you can stabilize the pH with calcium is around 8.3~8.5 due to the carbonate buffer system that we are stuck with. So to reduce the pH swing further, then the KH will need to be increased, which will bring your pH up.

There is only one other option...

You can start using a calcium carbonate product such as crushed oyster shell or crushed coral or Lithaqua or the many other formations out there. When pH swings as low as 7.0, then these calcium carbonate products attempts to create a more "natural" pH stable point. "Natural" in the sense that the product will bring the pH up to the point where other contaminants, such as algae, are poluting the water to cause the pH swing, but still the algae needs to be resolved. Even though calcium carbonate is based on the carbonate buffer, due to your low pH swing, this "natural" pH point will likely be around the mid 7s maybe, around 7.4~7.7.

You can get calcium carbonate products at any pond/aquarium store or at farm supply stores since this product is used to feed egg-laying hens. Put this product in an appropriate bag that allows water flow through it, like a fine-netted laundry bag, and then place this product in an area where water will flow by and possibly through it.


I am only recommending this above since you are showing a desire to keep the pH low, but, for the health of the fish and bio-filter, it is better to have a stable and constant pH and to do this is to increase the KH so the pH is near 8.3~8.5 and to increase the calcium so the pH does not go above this.


Unfortunately, there is only one buffer system that is easy for us to use, to not encourage further algae growth, it is the carbonate system we are left with. This carbonate system only has one stable pH point to work with, that is 8.3~8.5.

Now, I am told there are phosphate mines up in North Carolina and, if the water source is filtered through this rock, then the buffer system involves phosphates, which has 3 stable pH points (trying to recall offhand), and it is quite difficult to manipulate. So, I am guessing that your water is the carbonate system.

So, other than doing what I mention with the calcium, there is not much else you can do due to the algae's presence and as long as the algae is allowed to bloom. The "algal blooms" thread talks more about this in regards to how tough it can be to control algae.

 

[campingcreecher]

Only chemicals I have added to my pond have been Aqua Gold, and "Vanish" Sodium Thiosulfate chlorine remover, for water changes. Its always taken care of its self and the fish are beautiful. I order a new UV bulb from Atlanta Bulbs,(thanks for reminding me about them). Should I try an algaecide? (my hands are shaking as I typed that question) and if so could you recommend one?

 

[crsublette]

If you are confident that your bio-filter and bacteria in the pond is well established, by knowing you are never registering any ammonia nor nitrite on your test kits, then you can try an algaecide, but the typical algaecides are for complex algaes such as string algae, carpet algae, etc.

For pea green water algae, the algaecide that works is a proper UV device.

For the complex algaes, such as string algae, carpet algae, etc, then AlgaeFix works quite well, but be sure to know your pond's gallons and precisely follow instructions.

The thread, algal blooms, shares some more natural approaches.

 

[campingcreecher]

I feel total confidence in all our bio filtration. Just last month, I traded some of my last years spring koi to my local fish store. I gave them 12 of my least favorite koi babies, for a API kit and KH & GH kit. Dates are through 2017.
So I'm still nervous about using an algaecide since we don't have any of the other types of algae. I should get the new UV Bulb tomorrow. Mean while we will do a 20% water change later and hook the vac up and blow out the 2 sand and gravel filters. Oh yeah we have oyster shell in both filters too. hahaha Only thing we haven't done yet is hang a tarp or cover over up over the pond to keep the sun off. Yeah, that would look nice :/