# Algae or dust on pebbles



## Darkbluesky (Jul 30, 2015)

Hello,

Although I have a garden pond, not an aquarium, I am testing the PPS-Pro for fertilizing my plants.

Excuse me for the long description here below, but I thought it would be better to give some details of the system, before asking for advice:

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The pond is sunny with half-shadow because I put a cammo net above it to cast some shadows and reduce the intensity of the sun all day: the pond is south oriented and receives sunlight most of the day. In spring/summer, from 9:00 am to 20:00 hours, maybe a 15% of its surface is almost always in shadow but the rest is receiving light. Although the light is not like in an aquarium, that usually it is 100% from switch-on to switch-off. Here the incidence angle, the intensity varies (clouds, etc). The water lilies now cast shadows over the submerged plants.

At side of 5 water lilies, I have plenty of vallisnerias americana, valisneria spp, and 5 ludwigia rubin red, 2 ludwigia rubis, one ludwigia mini red, 2 althernantera rosaenervig, two althernantera rosaefolia, 2 echinodorus amazonicus, 4 egeria densa, some ceratophyllum demersum (which are very small now, due to last winter), and 5 anubias which did loss the leaves during last winter (they were inside at home, but they suffered too). They all are doing well with CO2 and PPS. They are planted on their own little pods (perfored pots), with H.E.L.P. Advanced Soil substrate and 1 fertilizer clay-ball of JBL Kugeln.

The volume is 3100 liters, and the surface about 5 m2, so the average depth (quite constant) is around 65 cm. Aside of submerged plants, I have also several iris, two types of papyrus, scirpus, etc.

There are several cascades and a little fountain. UV 35W and 12000 l/h pump with sponge+siporax filter + a lot of movement for cascades (~5000 l/h). The underwater DIY CO2 reactor moves 2500 l/h whose output flow is directed around the pond so a circular current is created (it is visible).

The bottom of the pond is covered of little clay bits, covered by big caliber beach sand and river pebbles. This bottom has done wonders: before it I had a lot of foam-like "algae" (I think it was not algae, but a kind of bacteria, iirc), now it has dissappeared. Moreover the beach sand do not get green algae on it, normally.

The water is a mix of RO-DI and tap water, with a final TDS of 250 ppm. NO3 = 5 mg/l, PO4 = 0.5 mg/l, CO2=14-15 mg/l, I add weekly Seachem Flourish and each 2 days ferrous gluconate to have 0.1-0.2 mg/l of Fe. pH=7.1, KH=7º dKH, Mg=7 mg/l, Ca=40 mg/l, K=15-20 mg/l, O2=9 mg/l.
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Now, I have CO2 injection with 15 mg/l, from 7:30 to 20:30 h. I close it by night as I can't waste CO2 (I need to inject more than usual, due to volume and surface agitation, which I don't want to reduce, so the consumption/cost increases quickly).

After starting PPS-Pro (1 week ago) the pebbles, stones, decoration, etc has started to develop a layer of ...green algae ?. The big stones, wooden log, etc have algae on it (very short -2 mm-green string-like one), and I still hope it can dissapear if I continue with PPS-Pro, but the bottom pebbles, has this thing over them. This is one of the few 'big' pebbles (around 2 inches long) but very most of them are half an inch, or smaller (sand):



This green thing can be removed with the fingertip (no need to use finger nails, just finger tip), and it reveals a pure-white stone. It is not present in the bottom of the pebble, only in the side that see the light. It appears in every pebble, regardless if it sees the sunlight directly or not. I have cleaned the bottom regularly (siphon and vacuum cleaner) but the pond creates normally some organic waste in between the valisneria roots, etc (they form a forest!).

Could you identify which algae is it ? It is really green (even more intense than in the image), but it can be cleaned off very easily. I guess they are not diatoms, because diatoms are brownish...

What do you think is it? And BTW, if you have some idea to avoid them, it will be always welcomed.

Thanks!


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## Diana K (Dec 20, 2007)

Yes, it is algae. If you let it grow I think this one gets rather large. 
I am not sure if algae eating fish would help. Perhaps a bit more shade?


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## Darkbluesky (Jul 30, 2015)

Hi Diana. Tx for answering.

I dunno which type of algae is (which is his name or family), I never saw it to grow long, though (I had it during the mild months of end winter begin of spring).

It is a pity about the algae eating fish, as they can't live here during winter. I should enter them to an inhouse aquarium and I would like to avoid all this hassle...


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## Michael (Jul 20, 2010)

I suggest that you stop adding fertilizer to the water column. All of your plants are potted in a fertile substrate which should provide all the nutrients necessary. Better to keep the nutrients in the substrate where they are available to the plants, and out of the water where they are available to algae.

Part of the reason your clay on the bottom of the pond helps with algae is that it absorbs nutrients from the water. Also, ponds in temperate climates usually have seasonal cycles of algae growth. My ponds typically show a lot of hair algae in late winter and early spring. The water is warming but the other plants have not begun active growth, so the algae has no competition. Also, the goldfish are coming out of winter dormancy and are eating a lot. Lots of fish food equals lot of nutrients.


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## Darkbluesky (Jul 30, 2015)

Yes these seasonal cycles are normal, I have them too. Thanks for the clay effect explanation, I was not really sure of this.

Before PPS I had always -according to test kit- PO4=0, and NO3=1 steady, which was shown in the plants. The bottom pebbles were somewhat greenish, as well as the stones, wood logs, etc, but its covering took a lot more time than now. Of course I would like to avoid this green covering, even being slow, but it seems that PPS has produced an accelerated and opposite sense, effect. ¿?

Without CO2, though, the plants melt and died even planted in nutrient rich substrate, so I guess that CO2 is a must... I have to add, that even with PPS + CO2 and plants growing well, they have some kind of algae on the older leaves, and the echinodorus in all of its leaves. It is the same kind of algae shown in the image of the stone in the first post, but not so dense. I mean, it seems that the plants thrive but not at full... I don't know what they are missing, (they have nutrients in water column and substrate).

Really the PPS description points to the fact that healthy plants inhibits algae, in my case it seems that it fuels plant AND algae grow, both. This seems contradictory with PPS theory about algae grow. I wonder if is possible to achieve an algae free pond.

Maybe I do not have enough plants for the nutrient load ? Then I have two options:

- Follow Michael advice and stop fertilizing (I hope plants will thrive as well as with it. I am not sure, for what I see these days), and be content with the slow covering algae...

- Add a lot more plants (fill the bottom with plants, but I have already a good bunch of them). But maybe it will not work neither...

Did you never found this kind of problem (this kind of algae) in aquarium ? I never had one, so I don't now. I am a pond-only guy...


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## Diana K (Dec 20, 2007)

If you need to add more fertilizer for the plants you could add another 1-2 clay balls to each pot perhaps a month into the growing season. 
Make sure your clay balls have a complete fertilizer, including macros and micros, then you should not have to add anything but CO2 to the water.


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