I can't believe it's been 8 days since I've been to this thread. Time flies.
That sure was some good discussion and ideas coming in for the cooling mechanics. I, for one, appreciate all of the input and I know others do too.
Well, let's see, what has ben going on...
The rock has been in the vat for 23 days at this point. It took 8 days for ammonia to peak and reach 0 and had it's highest point at 8 ppm. Nitrite came down to 0 on February 16 and it's highest point was above what my test could measure. Nitrates started to be measurable February 2 and started to climb thereafter. I was able to recharge the DI unit and get 300 gallons out of it before the tds started rising too much, so there was some water on hand to do changes to keep nitrate at a minimum. Diatoms started blooming on February 3. The diatom bloom has been far above what was expected and it has been a pretty good fight to try to get them under control, especially with the limited amount of good water that was available at the time. Most of the pictures make it look like there have been relatively few problems because the pics show the finished steps along the way and not any problems that had to be navigated to get there. Just to show that everything has not been smooth running as planned, check out the "beef broth" in the vat. The water is not as brown as it looks, just the diatoms covering the side walls and rock makes it look worse than it really is. At one point, it was so bad and had so many bubbles on the surface, I quite literally could not locate the thermometer.
After all of the John Guest fittings arrived, the RO systems were set up and tied into the DI units. The RO product water is coming out at 6 tds and the reading is 0 after the DI. One of the tds monitors was removed and now only the incoming tap, the RO product, and the final product after the DI are being monitored.
The color change of the DI has definitely slowed down tremendously. As of today, (Feb. 18, 2005), there has been about 1200 gallons run through the filtration system and the color has only changed down about four inches of the DI tower. About 1 1/2" of that was during the initial flush after recharging the DI again. Below is the full filtration setup with four 100 gpd 2-stage RO units feeding into the two DI towers. The carbon blocks on the RO units have 0.5 micron filtering ability so really, there is no need to run a separate sediment filter. The waste lines from the RO units are draining into the sink through four little holes drilled into the side. It really irks me to waste so much water, but "ya gotta do whatcha gotta do". The water is so bad here that there just was not another satisfactory option.
The color change of the DI unit can be seen easily now that the water coming into them is much more pure. Only the Kati (red) tower changes color from top to bottom as it is used up.
Two more skimmers were added to the vat but I cracked one of the bulkheads while I was doing that. The leaking bulkhead is losing close to 50 gallons per day out of the vat so I haven't fired up the other two skimmers. I have to go out to the greenhouse twice each day to pump in some saltwater to make up for the leak or else the water level gets low enough that the pump feeding the original two skimmers will suck air. At least the filtration system is set up now to be able to have the water to do that. Doing fifty gallon water changes per day ought to keep the water quality high and help fight the diatoms, unless the product water is high in silicates. Nitrates have not been measurable since I cracked the bulkhead and have been doing the 50 gallon daily make up. More bulkheads have been ordered to fix the leak and have extra on hand as well. The two bulkheads on this side of the vat are also plumbed to a cut down barrel which hopefully will allow the surface skimmers to run more freely. The barrel is then plumbed to the pump. The original two skimmers may also be plumbed this way if it works out to be better on these two skimmers. I will also run some Polyfilters to remove some of the organic load from the vat.
The surface skimmers need to be altered so they will pull more of the surface water. Right now, the surface skimmers must be kept fairly deep or else the pump begins cavitation as it will pump faster than the amount of water coming in. I mutilated some pvc 90's and these will be placed so the cut part will be parallel to the water surface. When the leaking bulkhead is replaced, the water level can be kept so it is just above the pvc fittings and hopefully will extract from the surface better. These surface skimmers will not be glued together like the first two were so they can be turned or adjusted as needed. When the original two get replaced, they won't be glued either. They are threaded into the bulkhead, and the whole assembly can be turned higher or lower in the water, but the fitting end can't be rotated to try to pull more from the surface.
David was up here again a couple of weeks back and we could barely talk to each other due to the noise coming from the blower's exhaust. (Running the surface skimmers free into the barrel was his idea- credit where credit is due.) With so few items running at the moment, the blower gate valve must be left partially open and the rushing sound of air is loud. When by myself, I can sort of tune it out and get desensitized to the noise. It wasn't until we were trying to talk to each other that I realized just how loud it really was, even though my sister-in-law had said she could hear it at her house about 400 feet away. (Smell that?- that's denial) A diffuser made for the exhaust valve was placed and now it is very quiet, the gentle hum of the blower running is all that is heard. Eventually, when all of the skimmers and lift tubes are placed, the valve shouldn't need to be left open at all, but for now, this diffuser will keep the neighbors from complaining.
Dealing with the diatom bloom has given me some time to think about some aspects of my plans. A few things I have been reconsidering;
I had made mention before that a few sunny days had elevated the temp of the water in the vat up to 84. The temp of the vat water never really came down even when it was cloudy for a few days. Maybe there are some other factors involved. With the blower only running a few items, (the two skimmers on the live rock vat and 6 lines bubbling in barrels to keep the fresh, buffered and salt water moving), the blower is making a good deal of heat. Trying to push air down to the bottom of five foot tall skimmers creates allot of back pressure on the blower and consequently makes heat. The blower only sits a few inches away from the vat and I think it may be contributing to the heat gain of the water in the vat. The furnace has been turned down for two weeks to keep the air in the greenhouse at 70 and the vat water is still around 80. The blower will be moved in the near future to be a few feet further away from the vat and see if the temp comes down any. I did speak to the supplier for the blower and he assures me it won't run near as hot when all the rest of the outlets are opened up so whatever the blower is producing will be flowing out freely instead of needing to throttle it back with the gate valve as it is now.
The furnace is also fairly close to the vat, about 18" away. It may also be radiating some heat to the vat. Even if it is not running, it radiates a fair amount of heat for some time until it fires up again. There's not much chance for the furnace to be moved until the plastic glazing of the greenhouse gets replaced. The furnace won't be running in the summer when the heat issues will arise so I am not too concerned about it at the moment. I do wonder if the tanks farther away from the furnace will run at a cooler temp than the vat sitting right under it. This issue may have to be addressed next winter. Hopefully the vat can be kept a few degrees cooler than it is now with a supplemental fan while keeping the furnace high enough for the rest of the tanks to be at a decent temp. Then, in a few years when the glazing gets replaced, the furnace can be moved higher if it proves to be problematic.
The tank stands are also being reconsidered. Taking up an extra 35" (7" per stand X 5 stands) on each side of the greenhouse is just not a compromise that would be beneficial, nor would having to leave out a tank or two. They would take up needed room to walk around, service the tanks and just make it unnecessarily crowded inside. In addition, if / when a tank needs to be broken down, the other tank on the same stand would have to be emptied as well. Instead of using 2" x 4" bracing on the outside of the tanks, (like little mini stud walls surrounding the tanks), internal bracing of the tanks or setting corner braces on the top of the tanks would save space. I have contacted the supplier where I got the material to build the tanks to talk about the engineering aspects of this. Most of the longer commercial tanks have center bracing, but I never have liked the look and functionality of them on top of the tank- for display purposes. With these tanks being dedicated to propagation, center braces would also make shadow lines in the tank during the day. That might be alright for some corals, but not for all. I was thinking that running strips of pvc sheet across the width of the tank, but in the water about halfway down the tank, would allow room underneath for live rock, leave room above for corals, and provide a nice support structure on which to rest "egg crate" panels. Triangles set inside the tank, standing upright and perpendicular to the side walls and bottom would connect the sides to the bottom and may be an alternative as well, or could be used in conjunction with the strips. A couple of negatives for internal triangles is that they would create corners at the bottom of the tanks allowing for detritus to accumulate there and would have to be notched to place "egg crate" panels. As far as the corner bracing on top of the tanks, they would be triangles placed on the four corners of the tanks. Again, my concern is shadow lines. I suppose they could be clear pvc sheet to help sunlight pass through.
Any one with some DIY experience engineering or building tanks is welcome to share their input.
) instead of requiring a thermal welder which was expensive to rent or purchase to weld poly plastics. The cheapest poly fabricator I found was in the ST Joseph-Ogden area but he still wanted over $300 per tank for a 7' x 2' x 18" which could have been made from one 10' x 5' sheet. I found a company in Minnesota who precision cuts rigid pvc sheet. They obtained the sheet, cut 60 pieces of 7' x 2' for the sidewalls/ bottoms and 40 pieces of 23 1/2" x 2' for the end walls, then freighted them to me for $2,927.40, which meant 210 gallon tanks could be built for less than $150. They would be of adequate volume for temperature stability, easier and cheaper to drill for overflows, and the material would be delivered to my door instead of having to pick up glass tanks in Rantoul and transport them home. When the shipment arrived, I checked the diagonals and the sheet was indeed cut perfectly. The plastic protective film was even still intact and the load was wrapped in cardboard and plastic so well, it took me and the driver almost fifteen minutes just to unwrap it. Not a scratch or chip any where. The only concern with the sheet was that it is only 1/4" thick, but with wooden forms it will hold. Only problem now is when I did the original graph drawings of the floor plan, I was drawing them only accounting for freestanding tanks and never made any new drawings to account for the extra space taken up by the wooden support frames. After building the first stand and noticing that it seemed to take up more space than originally thought is when it hit me that I hadn't gone back and made new drawings for the wider and longer stands.
) You could put foam insulation on the partition, or simply make it out of plywood. 
