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PH problem in ponds

A couple of my smaller ponds (less than 100L) are going basic, normally their PH is between 6.4-6.8, but in the past 2weeks a few are 7.2-7.6 and 1 got to 8.2.

To counter it I use spag, I throw a handful in and for a couple days the PH drops to 6.6-7.0, Most of them have CO2 generators and a peat or spag bottom.

I have never had this issue before, at first I thought it was the neigbours cat, as I have seen it urinate in the ponds, but I set up a few test tanks (4cm layer of spag in 2, 5cm peat layer in the other two then a 3cm sand layer) for the first week they are 6.4-6.8, but after a week they spike to 7.2-7.6.

Another odd thing is that my ponds in my polyhouse and a tank with a lid that coveres half the tanks top (mostly to keep rain from filling it) are holding a good PH range (6.4-6.6).

I am leaning towards either some form of animal has got in (as I have a new type of snail that has sprung up in my collection) or maybe an airborn substance, unless bacteria can do this?

So far it is confined to my collection I keep with me at uni and not at the bulk of my collection at dads (1-2hours north), and I have put a halt to moving any of my aquatics between the two.

On a side note many of my U.Aurea in these ponds are making red traps, I have a couple aurea varieties that go red anyway, but they normally have red stems and branches to go with the traps, perhaps this is a hint.

Any Ideas.
How do the ponds get water? Do you add water in them? I would check the water source. An airborne substance sounds possible.

That is so nice that your aurea are turning red. Could you post some pictures? My geminiscapa is a little pink at the tip. Sorry I don't know that much about pH issues.
I fill the water with water from dads, (a bore) the creek that shares the water has an array of carns, including drosera adelae, its PH is 6.9-7.0, I have been using his water on my carns for over 4years with no problems, other than that rain re-fills them.
It's likely mineral accumulation. When your ponds evaporate, the minerals that were in the water don't go anywhere. If rainwater makes up for all of you evaporation you wouldn't have a problem. But adding water which also contains significant amounts of minerals, such as from your bore (well?) causes the TDS to rise, often to insane levels. I think a comparison of the TDS, or even a simple hardness test of your ponds and the source water would prove interesting, if not shocking . I think the likely reason your ponds in the greenhouse haven't been affected is that evaporation is much less in a closed environment. You need to perform an actual water change on the affected ponds. Physically remove half the water, either by pumping or scooping it out, and refill with your source water, or better yet some collected rainwater.
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I took this issue into consideration when I set my ponds up, I also move every now and then (as I rent when at uni), so all of the ponds drain easillly from plugs or by a hose into a deep section.

I tried draining the ponds fully, hosing them out, placing new soil, then took the usual steps (let it settle 2days, added other plants like typha, nymphoides and nardoo back in, after repotting them ofcourse, then the utrics on the 4th day), same deal, good PH for a few days then back to basic.

I have noticed alot of 2 new organisms in the ponds that are effected, one looks like a snail (has a long shell) but moves rather fast, as well as some kind of aquatic moth larvae, I have never had moth larvae before, but the numbers are not high enough for them to pollute the water this fast.

I also have frogs swim in the ponds, but the ponds at dads also get many frogs and are fine, a couple ponds at dads place also have fish, prawns and crabs in them, whereas the ponds here do not, but unless the insects are the problem I don't see how fish could help.
Try this. Take a sample of the water you fill the pond with and test the pH immediately. Then let it sit in an open container overnight, with aeration if possible and retest the pH the next morning. See if you get a similar swing. Groundwater often contains CO2 in excess of what it contains once it reaches equilibrium with the atmosphere, and the pH will rise as the extra CO2 gasses off.
Ok, early this morning I grabbed two sterile containers, in each I put 200ml of my water originated from the same bottle, one has a lid on, the other does not, they are next to each other amongst the infected ponds, the initial PH was 6.8, this is "pure sourced" H2O, I say Pure sourced as it will not be 100% H2O coming from a bore, I know that the mountains behind dads place have Nickel, Iron and Tin, the rocks are mixed between limestone (very little), granite and clays.

Local carns on the Mountains include Drosera Adelae, burmanni, indica and spathulata, (also in the paddock are lunata), Utrics include limosa, nivea, gibba, aurea, minutissima, chrysantha, uliginosa and caerula, as well as byblis lin, all are naturally occurring, so the water is carn friendly.
The result are..... sealed container is 6.7 (the drop is most likely due to a temp rise as a result of being sealed) and the open container has risen to 7.1, after only 8hours.

If the problem is CO2 loss, why are ponds with CO2 reactors still being effected so rapidly, also why would the ponds in the polyhouse not be effected, granted the poly might slow the evaporation, but not to the extent of stopping it nor making a difference that lasts weeks. would it?
  • #10
Algae can cause pH to go up. A big bloom can make pH rise to 10.
  • #11
These are the pics
red traps (this is U.stellaris as I had trouble taking a pic of the Aurea in the ponds)

and typical red tips on Aurea

sorry about the quality

Thanks for sharing the pictures! Your plants look great, much better than the Utricularia I have growing outside. The red traps on stellaris look very unique.

This is probably not the cause of the problem, but have you added any new rocks or soil to the ponds? If so, maybe they are leaching minerals into the water, although that would likely raise the hardness more.
  • #12
Algae can cause pH to go up. A big bloom can make pH rise to 10.
During the day, and then overnight by sunrise it can crash into the 3s. Adelea have you tried testing the water at different times of the day/night?
  • #13
While I haven't had a pond in some years, I had found that boiling peat (over the use of simply long fiber sphagnum) provided a far more stable acidic pH. Previously, there too had been swings. I would keep some peat "tea" on hand if future adjustments become necessary . . .
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  • #14
PH is the same in the ponds at 6am, noon, 5pm and 10pm (6-7pm is night), I doubt algae is the problem as I can see very little and breed up and release daphnia and horn snail as needed, this has never been an issue.

I stopped boiling my peat as it seemed to increase the algae growth rather dramatically.

As for the red stellaris traps, it is only 1 variant of my stellaris that do this, and I think it may actually be a hybrid of stellaris and Aurea as the floats are different to typical stellaris, the flowers look like aurea on them and the plant is much thinner than typical stellaris.
  • #15
I stopped boiling my peat as it seemed to increase the algae growth rather dramatically.

That too had originally been an issue with me; though, by running the tea through a coffee filter to remove the peat solids, there were no further algal blooms . . .
  • #16
We had some rain so I collected some, the PH of the rain was 7.3-7.4 (varied over the 2days), this is here at uni, does that point to pollution?