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View Full Version : W/C's and drop in SG


bv_reefer
09-06-2007, 03:55 AM
-just wondering what do you guys do when you have to do a big water change and you're SG drops, do you're fish and inverts such as corals,anemones, and crustaceans get really stressed with the decent drop in SG? -i just found a snail thats been dead in the same corner for a week and it gave out the most putrid smell i've ever encountered, and i'm guessing it could also be part of my cyano-outbreak thats plagueing my sand..:neutral:

Aquattro
09-06-2007, 03:59 AM
I think most people here match SG BEFORE doing the change.

Static
09-06-2007, 04:10 AM
There should be no change in specific gravity when you do a water change.

bv_reefer
09-06-2007, 04:40 AM
i did test it before, it waz at 1.023 now it's at 1.021 if the hydrometer is right, but it was a bigger w/c at 20%

SeaHorse_Fanatic
09-06-2007, 05:19 AM
I have found hydrometers to not be very accurate.

bv_reefer
09-06-2007, 05:27 AM
:ya thats what i thought to, but i tryed 2 times with the same reading, 1.019!
i bumped it back up to ~1.021 for now

Captainhemo
09-06-2007, 07:06 AM
Really give those hydrometeres a good couple of bumps and make sure it is sitting on a level countertoop when you read both when you are checking the tank and when checking you new water before adding it. Just holding the hydrometer at the slightest angle can "bind" the float/pointer and give you an incorrect reading.
As long as your nrew water is at or above the SG of the tank, there is NOWAY the SG can come out lower

bv_reefer
09-06-2007, 07:22 AM
well i just put RO water, i didn't add salt because it was already at 1.023 so a 20% w/c with salt replacement would've kicked up to 1.025, i've never used saltwater as replacement water for a water change..

Pescador
09-06-2007, 07:33 AM
A water change is different from topping up evaporation.
Top-up with fresh water because salt doesn't evaporate but water changes are done with pre-made salt water at the right SG and temperature.
You drain a % from the tank and add the same amount of new water.
Try to make any SG changes gradually.

fishface
09-06-2007, 03:25 PM
get a refractometer. they're more expensive than hydrometer but one of the best investments for accuracy.

Jason McK
09-06-2007, 04:40 PM
A 20% water change with out and salt is insane. If your hydrometer read 1.023 without adding any salt I would have thrown the Hydrometer in the garbage and stopped the water change.

Aquattro
09-06-2007, 05:15 PM
you HAVE to add salt to your water change, that's the whole point!! You add water that is the same SG as the tank. And BTW, there is no way RO water was anything higher than SG of 1.000. That is pure water. Your equipment is either way off, or you're doing something terribly wrong...

Aquattro
09-06-2007, 05:16 PM
ok, I gotta ask...is there anything alive in this tank??

Rippin
09-06-2007, 06:51 PM
ok, I gotta ask...is there anything alive in this tank??

:lol: :lol: :lol: :lol:

Joe Reefer
09-06-2007, 07:05 PM
his sig says "33-gallon mixed reef & freshwater cichlid tank." So it must be like a brackish tank.:mrgreen:

Borderjumper
09-06-2007, 08:54 PM
Its also a good idea to let the newly MIXED SALT WATER age for a day or so before adding it to your tank.

I have never heard of anyone adding fresh ro water to a marine tank when doing water changes. Just cause you have "always" done it that way doesnt make it right. No wonder your SG isnt stable.

Borderjumper
09-06-2007, 08:55 PM
his sig says "33-gallon mixed reef & freshwater cichlid tank." So it must be like a brackish tank.:mrgreen:

Or its marine before the water change and then cichlid tank after the water change.:wink:

Jason McK
09-06-2007, 09:16 PM
Hey could it be possible he has used the term Water change when he meant water top-up.

BV-Reefer were are you?

Chowder
09-06-2007, 09:22 PM
He's probably at school.

Borderjumper
09-06-2007, 09:25 PM
well i just put RO water, i didn't add salt because it was already at 1.023 so a 20% w/c with salt replacement would've kicked up to 1.025, i've never used saltwater as replacement water for a water change..


dunno. What Im confused about is him saying that using salt mixture would kick UP the SG... BV ya do know you can always use a little less salt in the mixture and match the SG with your existing tank? As in make your water change water 1.023 IF thats what your tank is at?

bv_reefer
09-07-2007, 12:31 AM
ya i've been looking into a used refractometer but honestly i don't think that SG has to be super accurate for coral health as long as it's consistent

Jason McK
09-07-2007, 01:38 AM
I give up

Aquattro
09-07-2007, 02:04 AM
ya i've been looking into a used refractometer but honestly i don't think that SG has to be super accurate for coral health as long as it's consistent

Well, it has to be consistently accurate. Now adding straight RO to your tank kinda drifts away from this theory, dontcha think?

Rippin
09-07-2007, 02:15 AM
I give up

What matters is that you tried....


Ok, here it is -
Regardless if you are using a hydrometer or a refractometer:

1. When doing a water change, test your aquarium water's SG, then mix the replacement fresh water with salt to match this SG number. It does not matter if the water you are mixing the salt with is RO/DI or tap water - it will not make a difference in your SG levels. If you do this your SG will not fluctuate (by anything significant) during a water change.

2. When doing a water top-ff due to evaporation, DO NOT mix salt water for this, just use straight RO/DI fresh water and top off to the SAME level in the aquarium before the evaporation.

3. An SG reading between 1.023 to 1.025 is good. I would consider 1.021 too low.

michika
09-07-2007, 02:21 AM
It sounds like you need to pick a set point of specific gravity for your tank, and then read up on how best to maintain it. I'm not sure if your confused between topping off, and water changes, or if you just don't understand them out right.

Watch this ---> http://www.youtube.com/watch?v=kSTY346rros

In short, if your confused please ask. Many of us here are more the willing to help you out and get you pointed in the right direction.

bv_reefer
09-07-2007, 03:54 AM
ok, I gotta ask...is there anything alive in this tank??-no theres nothing alive, cause i just love growing cyanobacteria and hair algae for fun..

bv_reefer
09-07-2007, 03:55 AM
what ever all my fish and corals are growing great so no complaints so far, mind you i always do little water changes so the SG doesn't even go up or down really, just happened this time because i did a big w/c

scsi
09-07-2007, 04:49 AM
I think the point people are trying to make here is that your logic, regarding water changes, thus far is fatally flawed.
I haven't seen a light bulb go off over your head with respect to your first couple of really ummmm.... unconventional posts concerning SG and water changes.
Read between the lines..... you could do a 100% water change and not change the SG.........

bv_reefer
09-07-2007, 04:57 AM
I think the point people are making here is that your logic, regarding water changes, thus far is fatally flawed.
I haven't seen a light bulb go off over your head with respect to your first couple of really ummmm.... unconventional thoughts about water changes-ok ok i totally screwed up but it never caused absolutely any harm to any of my livestock so as you can imagine i never really made a big deal of it, but my w/c's are always small

scsi
09-07-2007, 04:59 AM
-ok ok i totally screwed up but it never caused absolutely any harm to any of my livestock so as you can imagine i never really made a big deal of it, but my w/c's are always small

Ergo, it's a top off......
Not a water change.......
Unless you're taking water out of the tank and replacing it with RO/DI water......
I don't even want to contemplate that gong show........

bv_reefer
09-07-2007, 05:01 AM
ok now you totally lost me...ergo?

scsi
09-07-2007, 05:03 AM
ok now you totally lost me...ergo?

therefore.......

Renegade
09-07-2007, 05:04 AM
The point of a water change is not to add fresh water its to add a new balanced source of sea water. Thats why people buy buckets of salt.

scsi
09-07-2007, 05:07 AM
The point of a water change is not to add fresh water its to add a new balanced source of sea water. Thats why people buy buckets of salt.

truckloads.... Aquacraft is retiring @ 55 because of me :mrgreen:

bv_reefer
09-07-2007, 05:08 AM
wow 4pg's..thats a new record for me..usually people give up at 2-3 :lol:, but seriously could this be the reason that i still have cyano bacteria, because i use fresh RO water?

scsi
09-07-2007, 05:11 AM
wow 4pg's..thats a new record for me..usually people give up at 2-3 :lol:, but seriously could this be the reason that i still have cyano bacteria, because i use fresh RO water?

well..... you really stepped into it this time
so to speak.......

Aquattro
09-07-2007, 06:08 AM
let's clear something up here. By water change, do you mean you are siphoning out 5 gallons and replacing with a new 5 gallons? Or did you let 20% evaporate and now you topped it up? There is a big difference.

bv_reefer
09-07-2007, 06:20 AM
nono i siphoned out 5 gallons and put a clean 5 gallons in...just fresh water though

Rippin
09-07-2007, 06:23 AM
nono i siphoned out 5 gallons and put a clean 5 gallons in...just fresh water though

Right, there's the problem. As you are most probably aware by now, you need to replace the siphoned 5 gallons with saltwater at the same SG.

ok, I think this thread is done now...:mrgreen:

Aquattro
09-07-2007, 06:24 AM
nono i siphoned out 5 gallons and put a clean 5 gallons in...just fresh water though

Ok, that is wrong. You need to add 5 gallons back of salt water of the same SG as you removed.
Now that we've cleared that up, you need to determine what the SG is now, using reliable equipment, and adjust if neccesary.

scsi
09-07-2007, 06:26 AM
no... we determined that on page 1 right away....
or did you not read that page?

bv_reefer
09-07-2007, 06:26 AM
i already knew my SG, it's 1.023 and i just made my 5-gallon of w/c water at 1.023 SG, so now i can do actual water changes :lol:

Aquattro
09-07-2007, 06:28 AM
no... we determined that on page 1 right away....
or did you not read that page?


I can't remember that far back. It's late. I'm tired. Someone needs salt is all I know.

Rippin
09-07-2007, 06:30 AM
He's seen the light!

Ok, time for beddy bye...

Aquattro
09-07-2007, 06:30 AM
i already knew my SG, it's 1.023 and i just made my 5-gallon of w/c water at 1.023 SG, so now i can do actual water changes :lol:


so there we go. But you mentioned your RO water was 1.021 or something, which it certainly was not. So if your hydrometr said it was, you need a new one, or different RO water. RO is always going to be 1.000. Then you add salt to 1.025 (my preference) and then add to the tank. Take some water to the LFS to double check your readings.

bv_reefer
09-07-2007, 06:31 AM
ok well problems solved, thanx again,...now that we're done here i'm sure
mik_101 will keep you busy with his ''HELP HELP HELP with yellow tang'' thread
:lol: :lol: :lol:

Aquattro
09-07-2007, 06:33 AM
ok well problems solved, thanx again,...now that we're done here i'm sure
mik_101 will keep you busy with his ''HELP HELP HELP with yellow tang'' thread
:lol: :lol: :lol:


sigh, yes.....

bv_reefer
09-07-2007, 06:34 AM
i donno all i know is that i tested my RO at 1.023 three times, so thats correct, and my tank water is also 1.023...so...i should be ok:smile:

Aquattro
09-07-2007, 06:39 AM
i donno all i know is that i tested my RO at 1.023 three times, so thats correct, and my tank water is also 1.023...so...i should be ok:smile:

K, trust me, RO is NOT 1.023, not ever. Salt water is 1.023. RO, which is pure H2O, has a specific gravity of 1.000 always, or it just isn't pure water. I'm not making this up, it's basic chemistry. If your hydrometer says your RO (from filter/store/wherever) is 1.023, it's broken. We can't discuss this, it's just fact. Or, someone in your house spilled a lot of salt in your RO bucket.

Aquattro
09-07-2007, 06:40 AM
so...i should be ok:smile:

Just to emphasize, no, you should not be ok...

Rippin
09-07-2007, 06:42 AM
ok well problems solved, thanx again,...now that we're done here i'm sure
mik_101 will keep you busy with his ''HELP HELP HELP with yellow tang'' thread
:lol: :lol: :lol:


Like two peas in a pod...

scsi
09-07-2007, 06:42 AM
i donno all i know is that i tested my RO at 1.023 three times, so thats correct, and my tank water is also 1.023...so...i should be ok:smile:

Yup... sounds good
you need RO water for your tank to replace the stuff that evaporates ( Salt stays in, SG rises)
you need water changes as part of good tank maintenance (old water SG out, new water same SG and temp in)

that Tang....... I dunno..........

bv_reefer
09-07-2007, 06:44 AM
no what i'm trying to say is NOW my RO water is 1.023, not before i put salt, come o even i'm not that bad! i know you have to put salt in RO for it to be salt water lol, i added a bunch of salt pre-mixed it in a 2L bottle and then put it in my 5-gallon w/c container

Aquattro
09-07-2007, 06:44 AM
Ok, like I said, it's late, I'm tired. But.....are you saying your RO is 1.023 BEFORE or AFTER adding salt to it? If before, it just ain't so....

Aquattro
09-07-2007, 06:45 AM
no what i'm trying to say is NOW my RO water is 1.023, not before i put salt, come o even i'm not that bad! i know you have to put salt in RO for it to be salt water lol, i added a bunch of salt pre-mixed it in a 2L bottle and then put it in my 5-gallon w/c container

Sheesh, ok, then it isn't RO water anymore, now it's SW. hehe, I'm going to bed.

scsi
09-07-2007, 06:46 AM
[QUOTE=bv_reefer;270198]i donno all i know is that i tested my RO at 1.023 three times, so thats correct, and my tank water is also 1.023...so...i should be ok

opps... I was thinking this of his RO water after he added salt

bv_reefer
09-07-2007, 06:46 AM
ya well he is my cousin lol, however i don't have the slightest clue how we both manage to make the worst threads:lol: (on the same day 2)

scsi
09-07-2007, 06:48 AM
I think he's playing us lol
there's no way in hell ro water comes out @ 1.023

bv_reefer
09-07-2007, 06:49 AM
no i ment it was 1.023 after i put salt...lol, fresh DI water at an SG of 1.023, that would be interesting..

Aquattro
09-07-2007, 06:49 AM
I think he's playing us lol


no, just a misunderstanding is all. I think we have it all sorted out now.

Aquattro
09-07-2007, 06:50 AM
no i ment it was 1.023 after i put salt...lol, fresh DI water at an SG of 1.023, that would make be interesting..

Well, that's what I've been saying!!!! You keep saying RO, but it's not RO after you put salt in. I think we're good now. Everyone go to bed, it's a school night.

bubye

scsi
09-07-2007, 06:51 AM
no, just a misunderstanding is all. I think we have it all sorted out now.

Ya think?
The title was a misnomer.......

bv_reefer
09-07-2007, 06:53 AM
Well, that's what I've been saying!!!! You keep saying RO, but it's not RO after you put salt in. I think we're good now. Everyone go to bed, it's a school night.

bubye-o sorry i always say RO even if it's salt, just to make sure people don't think i'm using tapwater, well thanx again...bye (by the way 7pg's! nice lol)

Captainhemo
09-08-2007, 10:54 PM
LOL, i miss a few days and come back to see 7 pages on this ...
And you thought it was record at 4 :)

Glad you've got it worked out now. Remeber to use that hydrometer on a flat surgace and always give it a couple good bumps/taps to make sure you're getting an "accurate" reading

scsi
09-09-2007, 05:11 AM
yah, I like threads like this :lol:

Aquattro
09-09-2007, 05:19 AM
yah, I like threads like this :lol:

liar

scsi
09-09-2007, 06:52 AM
liar

Liar huh?
Strong words...... You sure you didn't go to to bed when you should have?

not my bad

I love these kind of posts that follow the initial...
Because there was no nicey/feely answer to this issue... It was matter of fact.
OK... so some of us poked fun subtle like, and that was fine.... PM'ing..
But now you're calling me a Liar in public.... bad choice...
Yeah, like you don't see a big fat one ready for the taking.....
You admitted as much in your PM to me........
Remember Mod help? You just failed miserably as a Mod.....
"Checkmate".......
I'll change that to "Check"...... you wriggle out of this one..........
*** May be deleted by Adimins***
lol

Aquattro
09-09-2007, 03:18 PM
Liar huh?
Strong words...... You sure you didn't go to to bed when you should have?

not my bad

I love these kind of posts that follow the initial...
Because there was no nicey/feely answer to this issue... It was matter of fact.
OK... so some of us poked fun subtle like, and that was fine.... PM'ing..
But now you're calling me a Liar in public.... bad choice...
Yeah, like you don't see a big fat one ready for the taking.....
You admitted as much in your PM to me........
Remember Mod help? You just failed miserably as a Mod.....
"Checkmate".......
I'll change that to "Check"...... you wriggle out of this one..........
*** May be deleted by Adimins***
lol

:)

scsi
09-09-2007, 11:42 PM
over reacted.....
posted msg after being out partying all night....
sorry, didn't mean to be so rude