High pH


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Here I go again with another year of floating pond scum algae. Life has been busy but I hate to tear down my pond. I have 1000 gallons in almost full sun with about 6 small goldflish that have not been fed in 2-3 years. Every spring I vacuum out the muck with my pond vac. This year I added some of the bacterial booster stuff in the spring.

No runoff into the pond, water lilies and marginals only minimal fertilzer with pond tabs. EPDM liner, no reactive stones in water. Skimmer with 9.5 pondmag pump leads to a canister filter/uv with those sponges inside and then to a filto falls with bioballs and back to pond.

I can't do anything about the sun but my plants just don't do as well as they did several years ago. I'm not sure why. I am afraid of adding more fertilizer.

Our water GH out of the tap is about 0 for GH and very low KH. Last year, I used the ice melt product to slowly raise GH some and baking soda for Kh with I have to keep adding with new water or rain.

So here is my problem, the water is clear but the scum makes it ugly every sunny day. The only water parameter (other than struggling with hardness) that is out of whack is the ph which remains high - no matter what I do. It is always above 8.5 - 9.00.

Would this ph cause my plants to do poorly? Water Hyacinth will not live in the pond. I don't normally like to use chemicals but we are at the point of tearing it down if we can't fix it.
 
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High pH COULD affect some plants, but I don't think it would bother all plants. Maybe research a bit to see which ones like the higher range.

We were in the 9 plus range the first year or so, but slowly - while changing nothing other than allowing time to go by - the pH came down to a more reasonable range. I stopped testing at some point, so I don't remember the specifics, but things did slowly settle in.

Are the plants (other than the lilies) in pots or planted directly in the pond?
 
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Yea, I've had this little water garden for more than 12 years but it seems in the last 2 or 3 things have really gone to pot. I even did a 50% water change last year but it didn't help. I'm sure I'm missing something. My plants are all in pots. This was my first pond and I did dumb things like not have shelves for pots except for on one side - that's where the marginals are :)
 
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Sometimes items in the water like certain kinds of rock (limestone), coral, oyster shell, or cement, can raise the pH.
Oh my gosh, you might have something there. I do have oyster shells in the pond to try to raise the hardness.
 

cas

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Our water GH out of the tap is about 0 for GH and very low KH.
Did you test your pond water?
GH is the calcium and magnesium required for fish bone and scale development, and trace elements such as iron and phosphorous that are needed for plant growth. GH also bolsters Alkalinity which in turn buffers the pH, preventing any wide pH swings.

‘Higher’ plants have far more complex needs. The assumption that the fish waste (ammonia) will supply all the required nutrients is not true. At some point the plants will slow or even stop growing due to a deficiency in one of the other required nutrients. Fish poop provides nitrogen and phosphorus, and a few other trace elements but it contains no potassium, no usable iron or magnesium and very little sulfur or calcium. These all need to be added or the higher plants (plants other than algae) won’t thrive. If the plants are yellowing, they may need more iron.
 
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Charlotte, I haven't tested the ph in a while but here in New Mexico we have really alkaline soil and water, and our pond PH was around 8-8.5 last I checked. For me the trick has been to find plants that do well in more alkaline environments. Yerba Mansa has done amazing, water cress tolerates it pretty well, irises are holding up pretty well. The goldfish are doing fine. Water hyacinth also didn't work for me. Lilies have been doing well and provide shade to reduce algae. Green onions have worked well as a marginal plant. Just buy some from the store and plop them in the gravel somewhere.
 
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What causes plants to not do well? Other than specific preferences - I'm beginning to wonder if my hesitancy to fertilize the lilies (only using a couple of pond tabs in Spring) in an effort to keep organics out of the water is adding to the problem?
 
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About 6-8 hours of sun per day.
 

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Did you test your pond water?
GH is the calcium and magnesium required for fish bone and scale development, and trace elements such as iron and phosphorous that are needed for plant growth. GH also bolsters Alkalinity which in turn buffers the pH, preventing any wide pH swings.

‘Higher’ plants have far more complex needs. The assumption that the fish waste (ammonia) will supply all the required nutrients is not true. At some point the plants will slow or even stop growing due to a deficiency in one of the other required nutrients. Fish poop provides nitrogen and phosphorus, and a few other trace elements but it contains no potassium, no usable iron or magnesium and very little sulfur or calcium. These all need to be added or the higher plants (plants other than algae) won’t thrive. If the plants are yellowing, they may need more iron.
I have pond tabs... I have been afraid to fertilize much due to the concern about adding more nutrients to the water.
 
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Have you ever tried adding floating plants rather than only having the rooted ones? They can do a great job of mopping up excess nutrients in the water column and shading the pond to keep down algae growth. My pond is usually in the low 8s for Ph and hornwort does fine with that ph, for example.
 
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There are supplements you can add that don’t have nitrogen, like Maxicrop seaweed powder, dtpa chelated iron, and magnesium sulfate (epsom salts). If it were me though, I’d also provide some shade over half of it until the scum clears up, either plants or a structure.
 
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That my dear is af had some circulation on THE SURFACE made sure you skimmer was working properly and a good flow to the skimmer. regular maintence daily maybe twice a day to start.
It looks like theres no algae where the movement of the air bubbles are . even getting a power head or two would help.

but that scum as you call it is a sign of lots of organics in the water. lack of circulation and a filter that is too small and possibly not fine enough to do the job.

how often do you clean the filter / what do you have for a filter.

i saw you said the pond was 12 years old . you may just beyond what that pond can handle with the filter you have and the flow you are providing
 
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That my dear is a pond the algae is a sign that you have a large amount of organics and little filtration to remove it and or circulation. if you had some circulation on THE SURFACE made sure you skimmer was working properly and a good flow to the skimmer. regular maintenance ,daily maybe twice a day to start.
It looks like there's no algae where the movement of the air bubbles are . even getting a power head or two would help.

but that scum as you call it is a sign of lots of organics in the water. lack of circulation and a filter that is too small and possibly not fine enough to do the job. That algae also sas that the pond is living up to it''s part and has created the surface algae to help block the light to help absorb the surplus and keep the pond from becoming a bog with move land mass then water.

How often do you clean the filter / what do you have for a filter.?

i saw you said the pond was 12 years old . you may just be beyond what that pond can handle with the filter you have and the flow you are providing.

sorry for the repeat i just noticed half the text was missing . i have got to get rig of the dang gaming key board way to sensitive
 
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Thanks all, this was my first pond and I made several mistakes in construction - no inwall skimmer.

I have an in-pond Pondmaster mini skimmer with basket (no foam as it clogs too fast)

a Pondmag 9.5 pump hanging on the bottom of the skimmer

then water goes to a Oase Filto Clear Pressure filter systems with UV (it has those foam media pads - you can back wash to clean)

then water goes to the bottom of an Atlantic filto falls that is full of bio-balls media and fall back into pond.
I am 99% there is NO runoff water getting in the pond. I have about 6 goldfish that I have not been able to enjoy feeding for the last 2 years.

I don't understand where the organics are coming from if not simply the sun. I really don't want to shade - with the location a shade would just add to the eyesore that exists.

I have kept my pump size at this level because I hate loud waterfalls and it was a good size rated for my oase filter.
Is it time to tear this down?

The thing that perplexes me is that I have not changed my approach as well as I can understand and this floating algae has only become a problem in the last couple of years. What has changed? Darn if I know. Pond is beautiful on a rainy day.

I clean out the skimmer basket a couple of times a week or when it needs it. I backwash the oase filter weekly and rinse the bio balls in pond water every Spring.
 
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Sun isn’t a cause of your algae issues. As was mentioned excess nutrients/organics are always the root cause of excess algae. You aren’t overstocked with 6 goldfish in there no matter how big they are.

How much mulm/detritus is in the pond bottom? Is the pump still pumping as well as it was when it was new?

IMO, Filtration system is fine, you just need to up the circulation in the pond by another 1000 gallons per hour. In a pond of 1000 gallons, I would shoot for 2x the pond volume turnover per hour, so 2000 gallons, you are at least 1000 gallons short with 9.5 mag pump.

Also, looking at your pond, try faster growing plants that need to be weeded back more often, like water cress, parrots feather, water celery, forgetmenots, creeping Jenny, are a few that work well for me and are easy to pull out. If you haven’t yet, consider trying water lettuce and see how it does.

There are many ways to setup a successful pond, but there are a few keys that can’t be circumvented. Filtersystem be it an out of the box one or a diy bog, you need a way to remove excess nutrients from the water, be it through cleaning filter pads and canisters or pulling excess plants as they grow are both forms of this. Proper circulation 1.5-2x pond volume per hour and so it eliminates as many dead spots where crap can settle as possible. the smaller the pond the closer the circulation needs to be to the upper end. Your pond is fairly small, so circulation should be around 2x pond volume. Managing fish load whether it be size of fish or number of fish, to keep filter system from being over loaded. (IMO this isn’t your issue)

Things constantly change, just because something worked for awhile doesn’t mean it will continue to, don’t dwell on it used to or it has worked. It doesn’t anymore be it your pump getting old and slowing down, lack of cleaning of plant mulm from the pond bottom. Just focus on it being a problem to solve.

Ime plants are the great equalizer in keeping a pond and will hide many flaws to a point in a pond design or system be it in a bog or just in the pond proper. Choose the right kind of plants, logically the faster it grows the more nutrients it will consume in order to grow. Choose ones you can pull out easily, plant them bare root wedged between rocks, most of the plants I mentioned will just spread via runners just floating in the water.
 

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