I like clear water. I like green plants. I like green. If it were me, I would leave it alone. I believe fish eat algae, but I doubt that they would eat it all. I wold also bet that if you were able to scrape it off that it would just grow back.

Your pond is only 75 gallons? Unless I misunderstood your description, that's really not big enough for fish I'm afraid.

Is your algae stuck to the rocks? Or does it float around in the water when you stir it up?

Your volume calc may be correct, but if your shape is a true 2 x 2 x 4 then it would be 16 cu ft and 120 gallons. Either size is small but not too small for a couple gold fish. After all, there are much smaller aquariums. OTOH, if this pond were in direct sunlight, it might get too hot.

What above posters said - you WANT algae, just not the pea soup type. Im even ok with string algae myself! Have you read about the nitrification cycle - how in a healthy pond the ammonia from waste (plant debris fish poop etc) is converted by beneficial bacteria into nitrite, then nitrate which is what your algae and/or plants use to grow. So you need SOMETHING there to use the nitrate or eventually it can build up and become toxic to fish - if not algae then something else. Have you tried establishing plants?

A few minnows could work well - there's a cute pink variety. (Goldfish get too big - require about 50 gals per fish).

Thanks everyone, really appreciate the comments. I figured it might be useful to include some pics (I couldn't edit the original post but here are some pics) of the waterfall/pond. Sounds like this is probably a good Algae not to have to worry about.

To answer some of the questions earlier, the algae kinds of 'stirs up' into particles if I try to scrape it off, so it is not like a solid piece that I can just pick up and take out. It is like a semi-liquid form. Also, I do get direct sunlight on this pond (Southern exposure).

I had a hard time gauging the size of this outside of the vague measurements I took myself. I've never kept/maintained fish or plants in the pond before.

More questions (please let me know if this needs to be a different post, I figured some context with the Algae and pond size might be useful to ask the related questions here):

1. I was mostly worried about Fish poop becoming a maintenance hazard in this case but do you think it is practical to have one or two odd fish in here? Guessing Koi is out of question? I also have no experience with plants, specially with something this small

2.With the Sunlight effect, guessing I'll need to look into some plants or things for the fish to get some shade?

3. Also being an outside pond in a suburban neighborhood, should I be worried about Heron's and such making a dive for the fish and having to install a net? I am in the NorCal area.

4. Would it be an issue that the water gets circulated everyday (2 hrs/day) and I have a pump which basically takes the water from the bottom, sends it through an external filter and pumps back 'filtered' water as part of the waterfall from the top. Would it disturb the fish?

There is actually no reason that you have to get fish. You can use mosquito dunks to keep mosquitos from breeding. Most of northern CA other than Stockton etc re heat, would likely be ok for a couple fish; much better if there were some plants to soften the edges and create some shade. I have had a couple ponds for seven years. I started with three comets (little boring gold fish). My ponds are ~800 and perhaps 1200 gals. I have ended up with 17 fish in the small one and sometimes 30 or more in the larger unattended (no pump, no nothing) pond. The bigger pond now has one large fish but I doubt that he/she would have grown so large in constrained circumstances. Most others are quite or very small and we are talking seven years.

Please - no koi. These are LARGE fish 2-3 feet long and require as a bare minimum 500 gallons per fish (actually Ive heard 1000 gals for the 1st fish and 500 for ea additional) and a 4 foot depth. The myth about fish growing only to fit their surroundings is just that - a myth. Its more like the stunted growth creates havoc with the internal organs, and they die an early death (instead of 10-20 yrs which is the norm for goldfish and koi). If you've not had fish you may not realize how interactive they are and how attached you can get .... as you would with any other pet. You'll want to see them healthy and happy!

Theoretically perhaps it can be kept alive in severely cramped conditions by finding some way to maintain perfectly clean oxygenated water .... but what's the point? You want to see your fish (plural) moving around happily in schools - doing what they do - eating bugs, hunting for missed bits of food on the bottom - not just lying there like a sardine in a tin. They will even exhibit playful behavior .

As I mentioned rosy red minnows would be great as starter fish - they are naturally short lived and you would get a nice schooling effect with them in a small pond Perhaps a couple of goldfish but these are much larger fish, eat and poop a lot more and would require diligent partial water changes twice a week (use a vac to pic up debris off the bottom). On the other hand 75 gallons is really pretty small so it wouldn't be a terrible hardship to do 30% water changes but it really would need to be done or youll have water quality issues with or without plants bc of the high fish load.

Sorry don't mean to pick on you personally OP! Just have a passion for the well being of fishies is all. No need for koi - some long finned comets are virtually indistinguishable from koi and some shubunkins have amazing colors - only difference is they naturally are only 8-10 inches, not 3 or 4 times that size.

That's a lovely little pond BTW!

chas045 I wasn't looking to have fish to avoid mosquito's but just to host some fish and have a lively little pond. I'll definitely have to look into some plants for the fish to take cover during the day as it does get a lot of sunlight.

@kashka_kat Thanks for those suggestions, really appreciate it. Good to know about what fish will be happy in this much space. I'll skip on the Koi to start with, atleast till I learn the ropes of maintaining fish, I want them happy. I still need to learn more before I can commit to keeping some fish (I've read something about checking pH levels, slowly orienting the fish with the pond water etc) and ofcourse getting them some shelter from the heat - which means I got to learn about maintaining plants in the pond....

Hi everyone, I’m looking for some help if possible. Ive recently built a pond in my back gaden. It’s approximately 3200-3500 litres (750 ish gallons).

i have an pass 16000 filter and oase 10000 pump running with some oxygenating plants and three established lilies.

so here’s the problem- I’ve noticed the bottom of the pond is mirky, however when the fish come up towards the surface they are clear. See pics.

my question is , lots of people talk about crystal clear water but should the water be Clear all th way to the bottom like a swimming pool or is it going to naturally going to fur up anyway and the best I can hope for is surface clarity?

i had to top up the pond today with some tap water which in appreciat has phosphates that algae will feed on so it might get worse before it gets better but I’m just after some reassurance that what I’m doing is right.

ive got three koi 6 months old and 2 small gold fish. Currently about 40 cm of fish. Regs Chris