Think I should just do a water change or is there something more I should do?

HI everyone,

The readings in my tank are a little off. Do you think I should just do a water change or is there something more I should do? My tank is pretty well established, but the water level had gone down about an inch from the top of the tank, so I added more last night.

The current readings are:
pH: 8.2
Ammonia: 0.15 ppm (not an exact reading, but the test was between .1 and .25 color-wise on the matching palette)
Nitrite: 0
Nitrate:5.0 ppm
SG: 1.024

I feel like every time I do a water change, I have a fish die. I have two blue damsels in the tank that are fine, but as of this afternoon my watchman goby is no where to be found. I presume he is either dead or sleeping under the LR in one of his caves. Also, I noticed today that a few hermit crabs have just suddenly died...I can tell because their bodies are outside of their shells and they haven't moved all day, even when I put the cleaning magnet next to where they were sitting so that I could clean the glass.

Whats going on!?

Thanks everybody

 

First off... if you have ammonia and Nitrates, I would test your tap water.... you may have ammonia in your tap. In which case I would still do a water change, but I would use Prime to treat the water. Second... tell us more about your tank... size ... inhabitants.... how long running...etc.
That could lead to better advice.

Also I didn't know that hermit crabs were aquatic... I thought they were land lovers. ??? Guess I'm thinking of some other kind.

Edited to Add: Also I just realized that you are a salt water tank.... but the testing of the tap water advice is the same.... I'm pretty sure you can use Prime in a marine tank, or they make a marine version.

 

I used Prime once to fill up my tank initially and it was fine.

Also, I believe the hermits you are thinking of Genie are called tree hermits. Not sure though.

 

What are u using for a water source? I would prime the tank, that tiny bit of ammonia is deadly. MinI cycles can kill an entire sw tank

U might have found a hermit moult. My fw shrimp have an all clear shell I find. The sw hermits left me solid legs with a bit of clear film from off their body. I thought id found a dead one until I saw all 3 moving after I pulled the moult out

 

Thanks for the info, everyone!

It is a 46g saltwater tank that currently has 2 damsels and five hermit crabs. The tank has been running since last September. I just use tap water as a water source, and I mix salt and a chlorine neutralizer into it.

 

My guess is the water is mildly contaminated. Tap water has an aweful lot of random stuff in it (u might be surprised by what's on the local water boards reports and ok for human consumption. Were pretty sturdy creatures)

Sources for tsp water can change seasonally (ive seen threads where members need to use ro or other sources part of the year to protect their stock). With as long as tge tanks been runningbI would look at the water as the ammonia source

You may want to consider a new water source. Install a ro dI filter in your home, or purchase rodI fw and mix yourself or premixed sw from a lfs.

Prime is recommended for fw and sw

 

Awesome, thanks. Just looked it up on Drs. Foster and Smith! x

 

HI Dylan,
What temperature is your tank at, and what temperature is your change water? Are you matching your salinity?

Also, as mentioned, RODI is the best kind of water to use as it is nothing but pure water. If you can't get RODI, then RO, otherwise distilled water.

The problem with tap water is all the unknowns..... copper is a big one (could explain the hermits), along with other heavy metals, possible ammonia/nitrate etc.

Prime is definitely a good start if you're using tap water, but I would aI'm to convert over to RODI.

Regarding hermits.... do you have enough shells for them to move into as they grow? Hermits will fight each to the death for shells.

 

The tank is at about 77 F, and I bring the water to room temperature before I add it.

As far as salinity, I have been using Kent Marine salt. When I first set up the tank and did not yet have any fish in it, I would do water changes just adding fresh water, and I found that the salinity didn't change much; however now that there are fish in the tank, I always mix saltwater before I add it, but the water I add is at a lower salinity than that of the main tank...I found when I used to do water changes that when I matched the salinity, the overall tank salinity went a little too high (out of the normal range), but it could just be that I was adding too much salt to the freshwater that I was mixing(?).

Are there any RODI units that you prefer/would suggest? I have been looking, but I really don't want to spend more than $150... is that possible to do without winding up with a bad/so-so unit?

The tank is actually pretty loaded up with empty hermit shells...I made sure for the hermits that there would be lots of empties for them to upgrade to. I just checked today and what I thought were molts are actually the bodies of some of the crabs. I could tell because they were still in their shells, and when I have seen molts they have been just laying around in the water =(

 

Are you topping off your evaporated water daily?
As the water evaporates, only the water goes, the salt stays in the tank, gradually increasing salinity. This would explain why you need to use 'lower salinity' water at water changes.

I'm going to take a guess, but I think you may have unstable salinity, resulting in osmotic shock to your inhabitants. This shock can (and does) kill livestock. A problem that may be compounded by your tap water and what may be in it.

My regime goes something like:
- Daily, top-up evaporated water into sump using RODI
- Weekly, 10% water change. My WC water salinity matches the tank

Overtime, the system salinity falls marginally due to salt creep. If this happens, I simply add a little more salt to the next water change. But as a general rule, my display salinity never moves from 33ppt (1.025SG)

As for what RODI unit, I'm not familiar with US offerings, but I would encourage you to consider a minimum 3 stage filter. That is, one with a 1-micron sediment filter, followed by a carbon filter, through the membrane, and finished with the DI - These types of filters will generally always result in 0 TDS water.

Maybe something like:

Other offerings:

 

Oooh...actually, no I am not topping it off daily. So, you just top it off with fresh water from the RODI, huh? And then when I do a WC, that's when I should match the salinity. OK!

Do you treat the water that you use to top off the tank with something like Prime, or is the RODI water simply good to go in the tank without any additional treatment?

Those units look pretty nice...does it matter how many GPD you get?

 

I think you've got it
You should find that topping off daily with fresh RODI results in stable salinity.
Here's a good calculator that helps you see how your salinity changes with evaporation:

RODI doesn't need conditioning, it's pure H[sub]2[/sub]O - I don't use anything on my RODI (I have to remember to treat the water for my Freshwater tank )

The GPD may or may not be important to you.
In simple terms:
24GPD = 1 gallon per hour
Depending on how much RODI you want to make (or how often), you may want a higher rated unit.
NOTE: the GPD rate is influenced by input pressure and temperature. My unit will do 100GPD at 50PSI input, and 150GPD at 100PSI, and it slows down a little during winter.
You may also want to check the cost of replacement filters (sediment, carbon and DI resin), some may be more expensive than others - I get about 2000 litres (500 gallons) out of one set. And the membrane should be good for about 4000 litres (1000 gallons) - but of course everyone's mileage will vary based on their water source.

 

Cool! So, if the unit filters that much water per day, do you have to have a storage tank for the water, or does that just mean that that is the rate at it which it will filter the water when you turn on the faucet?

I'll definitely take into account the cost of replacement parts now when I'm looking at a unit now, too!

So, if I'm understanding correctly: (sorry to reiterate everything, but I think I'm learning lol) since I don't top off the water every day, and then all of a sudden add a few gallons at the end of the week, I'm having these salinity fluctuations that are causing the osmotic shock.

 

Cool! So, if the unit filters that much water per day, do you have to have a storage tank for the water, or does that just mean that that is the rate at it which it will filter the water when you turn on the faucet?

I have mine hooked up to the garden hose, and just plug it when I need to make water. I generally do it on Saturdays. I have two containers (suitable for potable water). One is for mixing my Saltwater in, the other is for my RODI Top up. I fill these once a week. For the RODI one, it sits as a 'reservoir' throughout the week, and I draw from it as needed.

So, if I'm understanding correctly: (sorry to reiterate everything, but I think I'm learning lol) since I don't top off the water every day, and then all of a sudden add a few gallons at the end of the week, I'm having these salinity fluctuations that are causing the osmotic shock.

Could be causing osmotic shock But yes, if salinity is rising throughout the week, and then you suddenly bring it down (with your water change), it will likely shock the live stock.

 

Alright, good to know! Thanks, ryanr!