New to hobby, need some chemistry advice :)

[clairebear]

Hi,

I got my tank secondhand one week ago, RSM250 with about 50kg of live rock, 9 fish and just a couple of soft corals. The water in the tank was being topped up with sea water before I got it. We managed to transport most of it and topped up with 40L Red Sea salt (this was provided by the aquarium movers so I am not sure if it was regular or coral pro). I am concerned about the chemistry levels, I want to get them perfect before adding any more livestock. I am using API for pH, ammonia, nitrite, nitrate and red sea for the rest and refractometer for salinity. These all came with the tank.

So once I did some testing the day after I got it:
Salinity: 1.022 (was low before moving)
pH: 8.0
Alk: 3.3meq/L9.2 dKH
Ca: 350
Mg: 1120
PO4: 0.04 (running about 0.08 usually)
Ammonia, Nitrite, Nitrate: 0

I have been dosing Red Sea Mg supplement 25mL/day as the instructions recommend not to raise the level more than 10ppm per day. I also did a 10% (25L) water change today, but I haven't got my RO/DI filter sorted out yet (came with t he tank, didn't realise there was no TDS meter) so I ot some more sea water from the LFS. Tests about 6 hours after the water change:

Salinity: 1.022
pH: 8.0
Alk: 3.1 meq/L 8.7 dKH
ca: 335
Mg: 1000
PO4: 0.08
Ammonia, Nitrite, Nitrate: 0

So my Mg dropped even though I have been dosing.. what am I doing wrong? Should I do a big water change with synthetic salt when I get my RO/DI filter sorted? Does anyone use the Red Sea supplements and do you follow the recommendations or only raising Mg 10ppm/day and Ca 20 ppm/day? Wouldn't doing a 50% water change or something raise levels by more than that? I am confused.

Any and all advice is appreciated Thanks

 

[DaveK]

First and most important, do not "chase numbers" to get your readings "perfect". If they are within an acceptable range, leave things alone.

Second, before worrying about any of the other parameters, your salinity must be correct. I know it doesn't sound like much but the difference between 1.022 and 1.025 will skew most of the other readings by about 12%.

Your tank seems to show a loss of calcium and magnesium after a water change. I suspect that your either not mixing the water correctly or using a low grade salt.

At this point, I would discontinue all dosing for the time being, and do water changes to adjust and maintain your levels. Test your newly mixed water, and make sure that isn't part of the problem. For most tanks, water changes will keep the parameters in line. You generally only need to use additives if you have large amounts of corals or clams that deplete calcium and magnesium faster than water changes can keep up with it.

When you do your water changes, do them so that you slowly raise the salinity. Then see where you are with calcium and magnesium. Your goal should be to replace most of the existing water, so you will need to make about 6 large partial water changes of 1/3 of your water.

Some other general considerations -

Make sure your test kits are good. Some do not give accurate readings. Perhaps a LFS can double check your readings for you.

Another key factor is how does the livestock look? if it's doing well, then you don't need to worry as much about the readings your getting.

 

[clairebear]

Thanks for the reply DaveK.

The water change I did was with sea water from the LFS, so I have no idea what it really is. I should get my TDS meter tomorrow, then I will make up some Red Sea Coral Pro in RO/DI (it is hard to find any other brand except for Seachem where I live so that's what I went with). So just to clarify I should do 30% water changes 6 times? And over what period of time would you recommend?

The fish are looking good, however the previous owner told me he didn't have much luck with coral and they are mostly not so great. But I am not planning on adding any more until I figure out all this stuff.

Thanks for the tip about salinity affecting other levels.

 

[ddelozier]

DaveK nailed it, SPOT ON. Water changes are your friend

Get a bucket/box of good synthetic sea salt, I personally used Instant ocean or Instant ocean Reef Crystals, depending on budget at the time. Go to walmart, purchase a 29g starter kit. These make great mixing/QT tanks. Setup the kit in a closet or out of the way place, not going to be doing alot with it atm. while at walmart, get 2-4 5g buckets(you will never have too many) At a LFS get a decent 900gph powerhead. You will also need a small 50-100watt heater(walmart may have em).

If you dont already have one, Go to BulkReefSupply.com and arrange to get a RO/DI(4stage plus system is basic and cheap). If RO/DI isnt in the budget rigth now, RO/DI water can usually be purchase from a machine local to you for 20-40 cents per gallon.
If you dont alread have one, get a Refractometer with calibration solution(dont trust plastic hydrometers, they lie....alot)

Once you have Salt, RO/DI water, powerhead, heater and buckets....you're now ready to make your own SW. With instant ocean, the mix is 1/2cup mix to 1g of water. with 5gal buckets, i usually make 4g at a time. Fill with water, add salt, get the powerhead going to keep the water moving, and set the heater up. within 24-48hrs, the water should mix completely, warm to 77-79ish and be ready to use.

With my 65g i change 12g every month. Get extra buckets. Siphon out a bucket, add new water slowly(preferably to the sump or Overflow)

Dont be afraid of mixing your own water. there is no magic water fairy that makes SW perfect... its up to you. You can also mix your water 29g at a time with the starter kit, just do the math. I have a 55g tank with a 300w heater, 2 powerheads etc. I try to keep at least 20g of SW made/warm at any moment. If i notice something suspicious in the tank, i do a 20g water change and check params.

 

[landshark]

Like DaveK and ddelozier state water change is your best friend in water chemistry. I would get a different salt like Instant Ocean or Kent Reef salt just get some other brand that you can get locally to test with. This will give you an idea of where your water parameters are before dosing for anything