Water change confusion

BayBud · 02-13-2008, 06:32 AM

Hi all.

Firstly thanks to those who have helped me with questions in the past, this site has been so far invaluable to me.

OK, i started my first marine tank about 9 months ago.
My tank parameters for the most part tend to be around this sort of level.

Salinity 1.024
ph= 8.1-8.3
temp 27-28 celsius
mg= 1200mg/l
ca= 400mg/l
Alk= 3-4meg/l

The tank is a nanocube 24 US gallon.
Up untill recently i was using Kent Marine nano two part solution (i forget the name)
I wanted to change the whole chemistry of the tank because frankly i was starting to see a trend where the Magnesium was too low compared to the calcium and as the kent nano adjusts both in a fixed ratio i wouldn't be able to raise the MG without raising the CA to a very high level.

Anyway back to my question (i confuse myself to readily on this) i have been attempting to make water for a water change

What im obviously trying to do is make sure the water change water is as close to my tank parameters as possible, so i add the correct amount of salt which leaves me usually at a reading of

ca= 220
mg = 540
alk = 2.06meg/l

I now run an airpump/heater in order to get the ph up to about 8.3, which it usually does within a day.

Ok, well recently i bought new chemicals- seachem reef advantage magnesium, and a grotech pro calcium powder.

I worked out the amounts needed to get this water chemically similar to my tank water but of course it didn't work like i expected lol.

Firstly i added the salt, let aerate and heat for 2 hours. Then i added the correct amount of calcium let aerate for an hour or so, then i added the magnesium and left the whole thing for a further two hours.

When i did the tests on the water change water the alk was at a massivley high level, im not sure how high but well over 5meg/l

Obviously i have completely misunderstood a fundamental chemical property here, but my question is how do i get the water change water ready without causing this massive alk increase.

BTW, the CA + MG tests for the water were exactly where i had predicted/wanted them to be.

Thanks for reading, i hope you can offer advice because im getting so stressed with this.

i should have mentioned the livestock situation, i basically have 4 peppermint shrimps and a couple of hermits, i was planning to stock up a little once i had understood the chemistry but it seems thats taking a step backwards lol.

thanks again

reef_guru · 02-13-2008, 06:58 AM

i wouldnt doctor the new water. what salt mix are you using? instant ocean seems to be the overall best, imop. i keep my tank at 1.026 which is nsw

BayBud · 02-13-2008, 07:09 AM

Hi reef guru.
The salt mix is one from Grotech, i forget whats it's actual name is i think its just something like reef salt.

When i make a batch of new water change water the CA-MG-ALK levels are far from my tank conditions.

Are you saying i should just put the water in as it is and make corrections only on the tank water?

Thanks for the help it's really appreciated

reef_guru · 02-13-2008, 07:23 AM

yup, just make the new saltwater and do a water change. if the levels are off, play with the tank itself. i supplement with a Ca reactor and liquid supplements to keep the levels of the tank where they should be. the key is to figure out the tanks dKH consumption rate.

mix your salt mix to 1.026 and measure the Ca, Mg, dkH
mix instant ocean salt mix to 1.026 and measure the Ca, Mg, dKH

and you tell me which ones better

BayBud · 02-13-2008, 07:30 AM

oh i dont doubt you are right.
I was sold this salt on the account that it was worth having but from my own experience i have noticed it to be far below par.

I think for the moment i will just do a water change, because i think this is far more important even if the new water isn't 100% than leave the tank without a water change.

For the most part the tank looks healthy, the encrusting sponges i had on some liverock are flourishing and the pepps are doing well, i just want to make sure i keep them happy, you know.

Anyway

Thanks so much for your help reef guru

Jason McKenzie · 02-13-2008, 07:33 AM

Baybud,
I would first figure out what the new saltwater levels are prior to adding anything. I would also use 1.026 as you salinity level. This might help.

I honestly didn't think your test results from the Kent Nano suppliments was all that bad. If all you needed was a little more Mg I would have just added a Mg supplement.
When adding supplements you will always be playing a balancing game. As each supplement will effect the other.

If I where you I would go back to the Nano supplements and just get some Mg buffer.

J

reef_guru · 02-13-2008, 07:36 AM

on a side note, i cant remember the last time i did a water change on my system. i check the parameters maybe once a week and there constant.

BayBud · 02-13-2008, 07:50 AM

Quote:

Originally Posted by Jason McKenzie

Baybud,
I would first figure out what the new saltwater levels are prior to adding anything. I would also use 1.026 as you salinity level. This might help.

I honestly didn't think your test results from the Kent Nano suppliments was all that bad. If all you needed was a little more Mg I would have just added a Mg supplement.
When adding supplements you will always be playing a balancing game. As each supplement will effect the other.

If I where you I would go back to the Nano supplements and just get some Mg buffer.

J

Hi Jason.

Im almost inclined to do just that, to be honest what threw me was how much correction would have been needed for freshly salted water.

Based on a 4 litre water change with a gravity of 1.024 (ish) it worked out as Ca=220mg/l MG=540mg/l and alk was 2.06meg/l
I think i shall investigate a new salt and at least try and get the levels as high as possible before i dose for maintenance.

I will certainly start raising the salinity, to be honest i only put it at 1.024 because of lack of understanding, on one hand people say 1.023 others say 1.026 (or even a little higher) so i tried to go for a happy medium untill i understood the whole machinations of the tank.

However it does appear that 1.026 is pretty much the staple so im going to gradually increase the tank to that parameter.

Jason + reef Guru thanks yet again for the invaluable advice

My sponges Pepps and i thank you

Best of luck with your own tanks

Baybud

reef_guru · 02-13-2008, 07:59 AM

bay bud:

Reef Aquarium Water Parameters by Randy Holmes-Farley - Reefkeeping.com

omard · 02-13-2008, 09:30 AM

Start using a standard salt mix like Instant Ocean or another one of the well known brands.

Forget all the additives period.

In a tank that size and age, frequent regular water changes highly recommended.

When you mix exchange water, use a good hydrometer to test. Make sure water is same temp as that in tank when testing and before putting in tank. You may have to heat water before testing for SG you are shooting for.

Don't use water right after mixing...letting sit for few hours with a airstone aerating it safer. Depending on water source you may also need a heater in mix water.

Keep accurate track of how much you need first couple of mixes...makes future mixing much easier.

Little room for error in exchange water for a Nano.

Good Luck!