Return to the Ponds & Aquatic Plants Forum | Post a Follow-Up

How long should I let city water 'sit'??

Posted by berlyn 9/TX (My Page) on
Mon, Oct 3, 11 at 10:23

I've been ponding for 10+ years. This summer has been h*ll with the heat and drought! My pond turned green, not the normal seasonal green. Green with a couple of inches of clarity. We tried everything to clear the water; natural & chemical, to no avail. After 3 months, my patience wore me down.

Our set up; 1100 gallon pond with a Skippy filter (quilt batting) with water hyacinth on top and a Sequence pump. Early this summer we drained 1/2 of it and I divided and fertilized the water lilies. I thought the fertilizer and the extreme heat may have cause algae bloom. I even shaded the pond, worried my fish might boil!!. That did not help.

I moved my Koi out yesterday, drained the darn pond, trimmed the water lilies (the chemicals were h*ll on them!), cleaned the bio filter and filled it up with City water. Day 2 it is still crystal clear. (fingers crossed)

My question is; how long do I need to let the city water 'sit' to evaporate the chemicals?? Should I really add a dechrolinator to my water??
Also, I have a smaller pond that is crysal clear & I am thinking of adding some of that water to help "balance" and get the good stuff going in the big pond. Thoughts??

I have never ever had this problem with my ponds, usually time and patience will clear it. Not this time!

Follow-Up Postings:

RE: How long should I let city water 'sit'??

I'd add dechlorinator regardless. I think 3 days would be enough with out.

Having lost an entire pond's worth of fish due to city water...I'm more cautious.

RE: How long should I let city water 'sit'??

I agree with Groundbeef. To be on the safe side I'd add a dechlorinator. I may be wrong, but I vaguely remember hearing that, while the chlorine evaporates, there are some chemicals that don't; chloromides or something like that.


RE: How long should I let city water 'sit'??

the worst thing is to drain your pond.water takes a long while to need to balance the pond with plants, not over feed your fish,and do a 10% water change and clean your pads each big is your filter and pump

RE: How long should I let city water 'sit'??

use a water conditioner, better than a dechlorinator.
here is one Ultimate

I have never used it. I only have small ponds that generally sit a week or two before I add fish!
Here is one with some Rosy Reds in it. Don't look for them as they hide in the jungle of plant growth!!

RE: How long should I let city water 'sit'??

You are right & draining was the last thing I wanted to do for that reason. Something is off in my pond that I can't figure out why. My bio filter is 50 gl skippy with water hyacinth floating on top. When I drained and cleaned the pond the filter media was not that dirty and yucky. I have a Sequence 750 3600gpm pump. I also have a small bog with floating hearts, watercress and elephant ear. I have about 5 hardy lilies and 1 tropical lily that has been blooming all summer long.
I haven't really been feeding my fish cause they can't see me or me see them.
This is not the usual green water/pea soup seasonal change. I know patience works best for that. It's green and rather murky with a couple inches of clarity and has been most of the summer. I noticed it started going green again late yesterday.
(Now our weather here is usually sub tropic and with this darn drought it's more desert like. I wonder if that is playing a part. When I say hot, we broke records with 40+ days of over 100'.)
I am thinking of taking my bio filter from my small pond and connecting it to the large pond in hopes of getting a jump start on the beneficial stuff and help combat the bad stuff that is taking over. Thoughts??

RE: How long should I let city water 'sit'??

berlyn, it sounds like you are doing everything sounds like the heat might be too much.have you tried a uv light. i would buy one rated larger than the pond, like the 36 watt tetra.that should kill the algae.also i never feed my pond plants my water is clear all more thing all that heat a 1100 gal pond might have gotten to warm.

RE: How long should I let city water 'sit'??

  • Posted by jalal z3/Canada (My Page) on
    Wed, Oct 5, 11 at 19:26

Don't know what your city water contains but mine has both chloramine and chlorine so must be treated as the chloramine will not break down without treatment and will kill fish very quickly. You also didn't say how many koi you have in your pond but a 50 gal skippy filter doesn't sound big enough for 1100gal pond. I had the opposite problem of you this year very cold spring and summer with only a few days above 75F so my plants were slow coming and had algae all summer long. Mine was because didn't have enough plant coverage and high phosphates in my city water. Tried some laguqna phosphate remover this year and it seemed to help.

RE: How long should I let city water 'sit'??

I have 3 8" Koi in my pond. I did add a water conditioner that removes chlorine & chloramine and nuetralizes heavy metals yesterday.
I also have a bog in addition to my skippy filter. I've never tried a UV filter, as I never have had a problem like this in my 10+ years of ponding.
Can you test for phosphate??

RE: How long should I let city water 'sit'??


1. Yes you can test for phosphates. Use a liquid test kit, the 'strips' are for crap.

2. You might also want to check your PH. I suffered a terrible crash earlier this year. Ended up buffering the water w/ some arm N hammer baking soda, then added some crushed oyster shells. This can help if you are having high heat/temp fluctuations. Keeps the PH more stable and it's easier on the fish.

RE: How long should I let city water 'sit'??

I believe after much debate with my better half, I have figured the problem out. I will see in several days if this was the root of the problem or not.
Luckily half way through this "process" (on day 2 of this), I grabbed my camera phone & snapped some pics.

I will post them later, when I read, how to do that.
Right now, I am too pooped & sore!

RE: How long should I let city water 'sit'??

Chloramine and chlorine will most likely react with stuff in the pond before it gets a chance to evaporate. Even a just cleaned pond still has a lot of stuff for the chlorine to react with. A chlorine test will tell you exactly when it's safe for fish. Much cheaper long term than a dechlorinator or having to buy new fish.

Ammonia is a by product of chloramine breakdown. Most dechlorinators convert the ammonia to non-toxic ammonium. Unfortunately ammonia tests see both forms as the same so there's no way to tell if ammonia is at a safe level unless the total is zero. So I think it's prudent to test ammonia and wait for a zero level.

Lastly, depending on your city, testing KH and adding buffer if needed, is also prudent as well as easy imo.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Ponds & Aquatic Plants Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here