AWC station plans

[Tastee]

I’m considering setting up a saltwater mixing station and automated water change for my Red Sea Reefer 250 (65g), and would appreciate any thoughts you have on my proposed design.

My RSR is in our dining room and I have an RODI station about 7` away on the other side of the external wall. I run an Apex and my RSR ATO is kept topped up from the external RODI reservoir via a PMUP and ATK. My Apex is housed in the sump of the RSR. The RODI station is outside in an enclosure to protect it from the elements. My reservoir is currently 80L (20g) but I have scope to double that if I need - I am allowing myself scope to install a second tank, maybe 120g or so later on.

My plan is to install another reservoir next to the RODI station (SW reservoir). This would be exposed to the elements but the area is a narrow side and quite protected. My reservoir will have a lid to prevent water and other pollutant ingress. I would provide power to the RODI station, and in that mount a DOS head and FMM. These would be connected back to the Apex base unit via a long Aquabus cable. Inside the SW reservoir would be a small powerhead to continuously move the water.

The FMM would control a PMUP in the RODI reservoir pumping to the SW reservoir. The DOS would be configured for AWC to pump from the SW reservoir to the DT and waste into the sewer (conveniently I have an entry next to the RODI station). The SW Reservoir would have an optical sensor (SWHigh) to detect when it is full.

I would have two new Apex outlets.

[SWCycle]
# Virtual outlet to trigger a saltwater fill cycle
#
Set ON

[SWFill]
# Outlet for the PMUP used to fill the SW reservoir
#
Set OFF
If Outlet SWCycle = ON Then ON
Min Time 120:00 Then ON
If SWHigh CLOSED Then OFF

Normally SWCycle would be manually set OFF. I would trigger a fill cycle by turning it ON temporarily and then back OFF.

I would calibrate the SW Reservoir with markings inside, so I know how much water it holds vs what it holds when it is full. After triggering a SWCycle I would add sufficient salt for the amount of water required to fill it.

The DOS configuration for AWC would allow for a fill Cycle, pausing AWC whilst a cycle takes place (sorry, haven’t looked into the DOS program yet):
IF Outlet SWCycle = ON Then OFF
Min Time 120:00 Then OFF

The concept is that the AWC would operate 24x7 draining the SW Reservoir. I would periodically add salt to the reservoir and trigger a fill cycle. As a failsafe I could add a second optical sensor to detect a low level in the SW Reservoir and disable the AWC.

Specific questions I have are:
1. How long can I keep pre-mixed salt in this configuration?
I use Aquaforest Reef salt currently.
2. How much water should I change daily?
I currently do a 27L/7g every 4 weeks (10% of total volume) so on this basis I would want to change ~1L/day (0.25g/day).

I would appreciate any thoughts the community has!

Thanks in advance, Brad.

 

[GoVols]

@jsker
This is right up your alley. AF reef salt and a Apex DOS setup.

Do you have any input for Brad?

 

[jsker]

1. How long can I keep pre-mixed salt in this configuration?
I use Aquaforest Reef salt currently.

Aquaforest dose not recommend more than three days, and I have mixed and used up to 7 days so far,

2. How much water should I change daily?

I started with a 10% and found that a 15% daily water change is working best for my system.

Warning my mistakes I see you are using 1+2+3+. Turn down the 1+2+3+ dosing to 1/3 of what you are dosing now and be ready to re-calibrate your dosing of 1+2+3+. I did not turn down the dosing and my numbers were all over the place. Also you will not have the even dose amounts after you get the dosing re-calibrated. Make sure your salinity is correct and I would suggest not relying on the Apex conductivity probe. I made that mistake also Fyi I was dosing 48 ml 8 times a day of 1+2+3+ and am now doing 16 ml 8 times a day of 1+3+ and 22 ml of 2+. I am sure as my system grown those amount will go up a little with consumption.

It has taken me about 6 months of learning and tune my system back in and my mistakes, but the system is looking great now

 

[Tastee]

@jsker, thanks for the reply and suggestions. Your tank is looking great!

If I can only get 3 days out of premixed SW then that is going to defeat a lot of the purpose of the mixing station (reduce manual handling). Thanks for the feedback.

I only have a small coral load at the moment, so don’t dose anywhere near the AF recommended amount. I had been dosing at 6 ml/day, but as I have added some corals in the past 2 months I recently increased that to 7 ml/day, as I could see my Alkalinity levels dropping.

I have found however that Ca and Mg are getting very high whilst the Alk is still lowish, so are increasing Comp 2+ (curr 9 ml/day) but leaving the others unchanged. I may drop Comp 1+ & 3+ back a little also if the Ca and Mg don’t drop a little naturally. I dose 1+ 02:30-10:30, 2+ 11:00-17:30 and 3+ 18:00-23:59.

Currently I test at Ca ~480, Mg ~1560, Alk ~7 or a tad less. I am targeting Ca ~430, Mg ~1400, Alk ~8 - testing with Red Sea kits.

I agree with you and don’t rely on the Neptune Salinity probe - it is for trends only. I test salinity using a refractometer, currently 1.025.

Here is my tank at the moment.