startup for ornamental pond

[singingpond]

I have a brief update and a couple of questions. I haven't seen the pond since my last post, but it still doesn't have circulation (electrician hasn't quite finished his work yet), and it has had only very sporadic doses of acid and chlorine over the now 3+ weeks since first fill.

My mom texted today that the water is starting to look murky, and that some of the underwater rocks look green. Of course, this is not a surprise. I offered to go over tomorrow and try to help with the problem... A few hours later came another text that the builder had showed up in response to my mom's complaint, and that he had added a gallon of shock, plus an unspecified algaecide.

A gallon of 12.5% in roughly 5000 gallons should bring FC up to about 25. There is no CYA in the water. I remember reading a post (by chem geek, I think) that the half life of chlorine without CYA is only about 35 minutes in full sun - would that apply here? Also, pH is likely still very high - would that have an effect one way or the other on the efficacy or half life of the chlorine?

I don't know yet what kind of algaecide was used - I will ask tomorrow. That is certainly an unwelcome complication. Do algaecides tend to mess up FC or CC test results?

 

[bdavis466]

Yes the chlorine half life is going to be very short and less effective since the pH is very high.

The main issues with most algaecides is that they contain copper and that may ultimately cause staining.

- - - Updated - - -

The algaecide shouldn't impact testing but it's hard to know for sure without actually knowing what was added.

 

[singingpond]

Well, I asked about the algaecide, but no luck, as my mom said they took the container with them. However, she said the material they described to her as an algaecide looked like a powder -- is there even such a thing? I thought algaecides were sold as liquids?

 

[bdavis466]

It was probably some sort of fairy dust. I wouldn't worry about it

 

[singingpond]

Yeah. Who knows what it was; but less hazard of having added copper to the water, I suppose, if it wasn't actually an algaecide. I wonder if they sprinkled in some powdered form of chlorine, along with the gallon of liquid shock, for good measure.

Boy is it frustrating to try to do anything on a pool that isn't in your own back yard, and that doesn't belong to you! A pretty darn obvious observation, I guess.

I may post again if/when I get another look at the pond, and some test results. Thanks!

 

[singingpond]

I had a chance to visit the pond today, and measured:

FC 0
pH 7.6
TA 80
CH 130
CYA apparently still 0 or close to 0 (dot didn't fade at all)

I measured CYA because we don't know exactly what the builder added to the water on Thursday.

As expected the large dose of chlorine added by the builder a couple of days ago was all gone. It looked like nuking the algae may actually have worked, however, as there was no sign of green today. There's still a lot of dust and dirt settled on the bottom (that was there even before the algae appeared, probably dust from the cement, and from dirt washing off the underwater rocks).

The CH level is quite a bit higher than it was when I first measured it on 9/6 -- it was 70 then and 130 today. TA has also gone up a bit, from 60 to 80. I wonder if the mystery powder that the builder added a few days ago might have been cal hypo... Or does CH normally go up in this manner simply from the curing of cement?

The water temperature was down to 67, and there is still no circulation in the pond, so adding stabilizer in a sock seemed a futile exercise. Instead, I added a pound of dichlor, pre-dissolved in a bucket, to try to get some stabilizer in there fairly quickly, as well as bringing up the chlorine (temporarily higher than necessary for chlorine level, but nothing like the levels of a few days ago). We'll check pH in a day or so, once FC is back below 10, and add borax if needed. Then probably another pound of dichlor, to get CYA up to ~25. [pond volume is estimated to be around 5000 gallons] Hopefully that will be enough stabilizer to allow maintenance with bleach until closing, which is probably less than a month away in this climate.

I promise to post a picture soon! I have several on my phone, but the phone doesn't want to talk to the computer at the moment...

 

[singingpond]

Sorry, this post was in the wrong thread, but I don't seem able to delete it.