How much is too much?

[Luky]

Just wondering how much is too much when doing periodic water changes?

I am fortunate to live in San Diego and I can go to the Scripps Oceanographic Institute Pier where they have large tanks of filtered sea water for aquariums available for free (I have not mixed SW in over 10 years). I just take four 5gal jugs there and fill them up to do water changes. I was doing this on my 40gal tank so about 50-60% every 3-5 weeks. I will dose with calcium, iodine, strontium/molybdenum, trace elements, (and buffer occasionally) on weeks when I don't change the water. I typically add about 2 gal of tap water every week for evaporation (treat with 5-10ml of AmQuel).

Tank is fish, live rock, big red and green mushroom colonies, big leather coral, big brown/green polyp/zooanthid colonies, some other soft coral (looks like skinny broccoli, but brownish), a pencil urchin, hermits, emerald crabs, brittle star, Asterina stars, snails, lots of purple/pink coralline algae etc. It was set up for the last 8 years. I just moved everything over to a 50 gal and got a 150w MH + actinic + 4 moonlight LEDs fixture, and a chiller and wanted to keep some other corals. I am just running a skimmer and a canister filter with carbon + phosguard. Had a CPR HOB refugium with fiji mudd and some algae in it (spaghetti looking stuff) with a light that I would harvest occasionally when it filled up. Don't think I am going to put the refugium on the new tank.

So is a large water change with real sea water bad for corals? I figure it helps remove whatever is building up from the tap water I use...

 

[ccCapt]

I would try to do maybe 20% water changes every 2 weeks. It will keep your water parameters more stable.

I will dose with calcium, iodine, strontium/molybdenum, trace elements, (and buffer occasionally)

Are you testing for all these things? Never dose anything you don't test for.

 

[jsmith]

I would try to do maybe 20% water changes every 2 weeks. It will keep your water parameters more stable.

Are you testing for all these things? Never dose anything you don't test for.

+1 do small frequent pwc not large unless there is an underlying issue.. and as stated never add anything you can't test for... but I don't see any issue doing occasional large water changes with sea water... but your better off doing small as stated.

 

[carey]

I vote for more frequent smaller changes as well unless an issue arises that requires alot of water be moved out.

I also would stop adding tap water for top offs. You go to the trouble of getting real seawater so you might as well buy some ro water from a lfs or from a supermarket water machine for like 30 cents a gallon. It will for sure help your corals and water parameters.

+1 for not dosing anything you arent testing for. You especially, youre getting NSW from the ocean so it will have everything you need. And if you do weekly pwcs you are replenishing any elements that are used up through out the week.

 

[PsiPro]

buy some ro water from a lfs or from a supermarket water machine.

Make sure it is ro/di, my supermarket only has filtered water.